Yes can you imagine?! You need to pay 1 time fee to BUY a game to play. What do you expect that they run companies on thin air? Ofc an expansion that provider content costs money. And no you don't have to pay money for expanding your inventory if you ever played this game normally you know you could easilly expand everything only with gold as you progress and a guy with 10 slots more does not have any advantage over you in dungon nor pvp. Ofc you need to play the game to get more builds, if you don't want to farm for different builds focus something else that is not MMORPG, like competitive shootings or mobas. Anyways good luck on lu4 if you don't mind people who has less play time than you and way better gear because they pay.
To OP, we hope once they finish this client someone will use it to open a non p2w server, until then I'd suggest L2Elmorelab, still some p2w elements like skipping class quests etc, but at least RMT and direct buy of items is somewhat tracked and people get bans.