For everyone using Lugia..

Play on the casual ladder if you don't want to play against the meta.

Nope. I'm not gonna burn what few Credits I have on building some random deck that's probably gonna get destroyed in Ranked by people playing better decks. If the game's gonna give me a perfectly good deck entirely for free then you bet I will use it xd

The "you lack creativity" argument is so old that you can practically see the cobwebs growing on it. And it never works. There's no point in reinventing the wheel and in any given meta there will only be so many decks and cards that are up to a competitive standard. That's not to say Lugia is the only playable deck; there are others that you can more than less build using the things the game gives you for free or using a reasonable amount of the in-game currencies. To name an example, Mew VMAX is a solid deck that you can probably complete within your first month of playing buying the bundle + using credits to complete the missing pieces. But even if I did that, by your logic I'm still not "being creative" because I'm not doing anything new; plenty of people play that deck.

This complaint also shows a lack of understanding of how deckbuilding works and it's based on a questionable definition of "creative". If all you do is copy/paste a list from the internet and never change anything, sure, I could give you that that's not very creative. But that's also not what most people do; it's far more common to look up a list to start from a base but then doing several modifications to suit your playstyle and to accommodate to the matchups that you feel like they give you trouble. The way in which you tech out your deck and the exact proportion of cards that you use do require thinking and can show the creativity of the player.

To continue with the Lugia example, while the core strategy of the deck will always be the same (use Lugia VSTAR to get 2 Archeops into play), you'll rarely find 2 Lugia deck lists that are identical. There's a lot of room for variation. How many Lugias do you run? A 4-3 line is fairly standard, but maybe you're greedy and you run a 3-3 line to save deck space; or on the contrary, you try to play it safe and play a 4-4 line. Do you run any Blissey V to reuse energies? I've seen several lists that do, and even a few that rely on it as the main attacker, but I don't. Do you run a Radiant Pokemon? Which one? Charizard seems to be pretty common, but I've seen lists with no Radiant Pokemon. Radiant Hawlucha seems like an attractive tech against VMAX decks since Lugia can struggle to OHKO VMAX Pokemon. Radiant Gardevoir and Radiant Jirachi also seem like attractive options. How many energies and which ones do you use? Archeops can accelerate a lot of energies but Lugia's attack costs 4 and it's not rare for you to be low on energies towards the end of a match. Somewhere between 14 and 16 seems like a good number, but going on the higher end you have higher chances of bricking. Running 4 Powerful Energy seems like a no-brainer but other than that the other energies are entirely up to each player to decide. How many V-Guard energy do you use? They don't stack but having more means you can protect more Pokemon. How many Capture Energy? They help set up but don't provide a direct combat benefit. How many DTE? There are situations where you need the extra energy, specially if you can only get only 1 Archeops up or if you're locked out of using Lugia VSTAR's ability, but the -20 damage does hurt against other Pokemon V (specially agaisnt VSTAR and VMAX). How many trainers do you use and how many of each? The only thing that you're for sure using is a ton of Ultra Balls, Evo Incense, Quick Ball and a couple of staple supporters (Professor's Research and Marnie). But exactly how many of each? Research is really good in general and the deck does need ways of discarding the Archeops (as many as possible), but many times you'll find yourself with hands you don't want to discard and Research will be your only out. How many Marnie? Being able to save your cards is nice, but sometimes you need to draw more than 5 cards and the ability to discard the Archeops + things you no longer need provided by Research could be more valuable. How many Boss' Orders + Serena do you run? Serena can only gust Pokemon V but it's a much more flexible card, while Boss' Orders can sometimes end up being a brick but there are matchups where you absolutely need to gust a non-V Pokemon. How many tech supporters do you run? Professor Burnet and Cheren's Care are both really good as well as fairly standard choices, but maybe there are some crazy ones that could be useful situationally. Right now I'm experimenting with running 1 copy of Roseanne's Backup, which I've never seen on a different Lugia deck list. I'm thinking that it might help me clutch out a match where I'm just barely 1 energy short of winning, or where I absolutely need to get a Pokemon or a Choice Belt back into the deck. Do you run any stadium cards? They aren't searchable in this deck but they could have some benefits. Do you run Path to the Peak? You could potentially wall entirely decks that rely on V abilities, but it also stops your own Lugia VSTAR from setting up Archeops so you have to either drop it after you use your abilities or you have to plan on using it to buy time and then removing it yourself by dropping a Pumpkaboo; it also has the disadvantage of you not being able to use it to remove your opponent's Path to the Peak if they drop one before you can put Archeops on the bench. And I could probably keep going.

So, as you can see, there is an organized thought process behind building your own Lugia deck (or any deck, for that matter). While you could just use a copy/pasted list, and it's definitely fine to use a copied list for a few games just to get a feel for it, most people will carefully examine the list and create their own version of the deck. This requires not only a good amount of thinking but also a certain degree of creativity. Creativity isn't limited to just building new things; optimizing and personalizing something that is already know also takes creativity.

One last point that I'd like to make is that deckbuilding and piloting a deck, while related, are different things and therefore require different skillsets. And not only that; they may also point to different interests. Some people might just not enjoy making new decks, but they do like playing the game. For them, there would be no point in trying to make crazy new decks; they would rather take a good deck into ranked and grind games. In the time that it would have taken them to theorycraft a new deck, gather the resources to actually build it, test it, refine it and eventually come up with a finished list, they could have probably played several dozens of games instead. On the other hand, some people derive their enjoyment from building new things from scratch and experimenting with them (which may or may not be your case). And that's fine; not everyone will enjoy the same things. But you gain nothing from calling out the former for being uncreative. They just want to play the game, and some guy telling them that they're playing the game wrong will not move them.

Live's economy and card design contributed to this problem.

Most people use the cards given in the game. What's more, card design make it powerful.

Lugia is the F2P deck....

why should I build a random deck that costs more credits than building top meta deck, when I have limited credit?

I have claimed every reward in the game and now all I can get is 60 crystals everyday (and coins are useless).

how am I supposed to build another deck?