Well here's an unpopular opinion. I'm not sure if it has been said already (it probably has) but I think there is just too much content in this game. Am I crazy? Maybe. But I feel like when you have so many stages at your disposal that you sometimes forget which ones are there and you stop appreciating them. The same goes for characters. The CSS is just filled to the brim and sometimes I forget "Oh yeah Duck Hunt is in here." These characters start to become less special because their faces are lost in the crowd. The more you have the less likely it is someone will try out a character and give them a shot.
So yeah. I really think less is more. Sakurai and his team could have focused more on making a somewhat smaller roster and making those fighters even better instead of trying to cram everyone in there. Yup this is an unpopular opinion for sure. But I'd be happier with a roster of 65 fighters and 70 stages. That's plenty, honestly.
The problem with this ideology is that I don't think less is more when it comes to Smash. The amount of love, time, and care put into everything Smash related and make most of them so unique that it's all quality content to a person like me and a great many people on this forum I think. Less doesn't really become more for Smash, it's just less. I feel like they did tons of tweaks and updates to character while bringing everyone back and while also bringing in new fighters and content. Just because some characters are less likely to be tried out by some people doesn't mean you should cut characters either, they still add variety and content to the game. Hell, the roster's generally well balanced (Little Mac aside) and I just don't actively see how the game really seems to have suffered from the decisions they made except with regards to maybe a couple of modes.
There's also the issue that I think a few people are very desperate to see certain characters cut because they don't align with their personal ideologies of what should or shouldn't be in Smash, and a lot of them jump on to this ideology since it's seemingly the perfect opportunity to do so.
Well in regards to stages I feel as if a lot of them are either redundant or something barely anyone likes. Do we need both Smashville and Town and City? And very few people really like Hanenbow. But in regards to having fewer returning stages I think it would have allowed the development team to make more brand new stages. We only had three new stages in the base game because they spent most of their time recreating and refining old stages. And honestly I'd rather have a few more brand new stages instead of them trying to bring back as many old ones as they can.
As for characters, Sakurai himself said that because the focus would be "Everyone is Here" that there would be less newcomers as a result. I'm always in the camp of prioritizing the new over the old. It's nice to see a few old faces return but honestly it's not on the top of my list of things I'd want to see in a new Smash Bros. New characters and new stages are.
There's quite a few more Hannenbow fans out there than you think my friend, myself included haha.
The big thing with "Everyone is Here" is that it allows all of the DLC to be newcomers. It lets all future content be new content and we don't end up in a DLC cycle where we're just seeing characters return. I think that's part of the decision making behind Ultimate. It makes for an ideal platform to only add new stuff, which may prove beneficial given the game's early appearance in the Switch's life cycle. Furthermore, "Everyone is Here" also proved something else: It was a smart business decision. The game sold 12 million goddamn copies in the first month of sales and the game had a hype campaign I've never even really seen the likes of before. It actually worked super well from a business standpoint. You may value newer content more, but consumers spoke a LOT to how much they collectively value that older content and the idea of including it all/most of it in one release.
If it makes you feel any better, future iterations will have to focus on new content one way or another. Either a reboot that redoes many thing or an Ultimate 2 that just uses Ultimate as a base and allows for much more new content. This was clearly Sakurai's attempt at a true and definitive Smash that encompassed all of his work.
Everyone knows this, but cutting characters is just a fact of life for fighting games. The more you carry over, inevitably the more work you have to start off doing as a baseline. You can't just increase the roster every single game and make fewer and fewer content and more clones to compensate.
For example, USF4 had a ginormous amount of characters, and SFV decidedly less so, building on that roster as time went on. How many people would cut newcomers from SFV like G, Necalli, Kage, Rashid, Menat, or Zeku to bring back Rufus or Hakan or Dee Jay or Honda or El Fuerte or Abel back? Not many I would imagine, and for those that do want those characters, the previous version would always exist.
Street Fighter V was the epitome of greed and rushed development on Capcom's part and continues to be a fairly miserable profit driven product for it. 16 characters at launch for a fighter is ****ing embarrassing and unreasonable, and while stuff like this might be more standard these days, it's still disgusting. Street Fighter V should never be a comparison anyone uses, period. It may be a general fact of life for fighting games, but Smash isn't just another fighting game and a decent portion of the fighting game community hates hearing it be called one lol.