I think one of the problems with Smash discussion is that it's one of the biggest budget franchises from a company known for and open about making most of their products cheaply, and primarily features characters from older; ubiquitous; or niche games - and therefore it's judged from the same standards as the smaller games it represents and shares Nintendo Direct space with because its fans aren't familiar with Smash's proper triple A peers, and never stop to think of Smash as a big; hypermarketed product that needs a high level of scrutiny just because it doesn't have Dorito bag promotions like Halo and CoD, while also assuming all games could have as much content as Smash regardless of budget or niche factor.
Video games are something with a like half-century long history with a lot to it and a lot of people to please. The only way you could even begin to create a (fighting) game that really qualifies as a celebration of gaming would be to have an absolutely massive roster, created by a new, completely independent development team for the specific purpose of creating such a game (with all the funding and resources available to the biggest name games). That can also meaningfully implement aspects of gaming history into the game that might not translate well into playable characters.
But it's not something that we can expect to happen, it would be a task possibly more enormous than the industry has ever tackled before