A lot of modern arguments in relationship to Smash it boils down to when you got into Smash or what aspect you love about Smash.
For me, when I first got Smash 64 the only characters I knew were Mario, Luigi, Donkey Kong, Yoshi, Pikachu, and Jigglypuff.
So I asked my dad for Kirby 64 and would always play Star Fox 64 at my cousins house. When Melee came around I was able to play some Zelda and then later Fire Emblem, Metroid and F-Zero. During the 7 year wait between Brawl and Smash 4, I was so hungry for more I collected the trophies and read all of them. It made me incredibly curious about the worlds of people like Mach Rider and Custom Robo. After the SSBB e3 trailer (the most hype trailer ever imo still) I went on the official Nintendo forums (NSider) as a kid and debated people about what characters would appear in the game. I was completely in over my head, but in order to show off I literally just bought or emulated every Nintendo series I could find. I found out about Sin and Punishment, Golden Sun, Advance Wars, etc. during this time. The inclusion of Snake also got me into non-Nintendo games. NSider was awesome, it was pretty cool how Nintendo ran a forum for their fans.
Before Brawl's release, Nintendo abruptly shutdown the forums. If you remember the early to mid-late 2000s, Nintendo had the my Nintendo fun club and just gigantic support for all of their franchises. Like damn.
https://sickr.files.wordpress.com/2014/05/nintendo_family_tree_infographic.png
Sexy gen 6/7.
During the last leg of the Wii's life, the fan forum was gone and turned into a corporate "maintenance" forum and a lot of these series had died or became dormant. During the console wars of that generation, Sony and Xbox fanboys loved to throw around "Nintendo is just Mario, Zelda, and Pokemon", well during this time it pretty much became true. A lot of new blood joined the world of Smash during this time before Smash 4's announcement. So to a lot of people Smash stands for something else.
Still, to me, the ideal function of Smash is a fun museum. I don't know the guy, but I have no other idea as to why Sakurai would put a list of every single game published by Nintendo in Brawl. Tin Star was on that list. That game is not going to get more sequels, its not going to make more money. That could've been time to crack a viral joke about Spongebob/Michael Jordan/Transformers movies for more publicity, but nope he spent time and resources and made that huge list instead.
Course I know people want it to be a billboard too. Why not a good mix? The most painful comment I read in relations to Smash Ultimate news was this.
Damn. Simon and Richter are legends. Steve is pretty important. Then support him, but don't rag on people wanting Banjo, Geno, Isaac, Bandana Dee, or whoever.
If you love Dragon Ball Super, you don't have to insult Dragon Ball. If you like Lil Peep, you don't have to insult Biggie Smalls. If you like Nintendo Switch you don't have to insult the SNES. Smash gives Nintendo something so unique, it gives a dead series or character popularity needed for a new game.
tl;dr
Thank you Sakurai for letting us hear new renditions of Mute City, visit 3d Onett, reviving Kid Icarus (which made money) , hearing a melody of Joy Mecha Fight and Urban Champion, bringing us Fire Emblem (which made money), giving Samus a job while she had to wait through Federation Force, and more.
(and not doing that Tekken thing where you put in a Walking Dead character for money. why does sakurai not do this? mario, pikachu, sonic, and link are on the box. its going to sell well already)