When I play a game I like, I usually do my best to play all the games in the series (sequels and prequels, and often spin-offs too) because I become a fan of the franchise.
I prefer to stick with a limited amount of franchise I like rather than playing a wide range of random stuff.
I started being a gamer during a time when I liked almost all the stuff Nintendo released, with some exceptions, so I became fond of all the iconic Nintendo franchises. This happend starting from the SNES/GB generation to the Gamecube/GBA generation. With the DS and Wii, Nintendo started to shift the focus to casual gamers, and developed a huge amount of games I didn't like... even their core franchises got influenced by this shift in target audience.
I also play on PC, and very rarely on other consoles too (I don't own them, but some of my friends do, and it happens that I may play something at their home).
This is why I'm not much interested in most third parties, I know some of them are good and all, I just don't want to follow too many franchises because it's expansive both in money and time* (*I played the Dark Souls trilogy and I decided to not play any other Souls game after that because I usually spend more than 200 hours each and I don't want to, despite I like them).
Though, I'm starting to lose interest in some Nintendo franchises to... some of their recent games just don't interest me anymore as they used to in the past... I was a huge Zelda fanboy, but I think the Zelda games became less and less interesting from Twilight Princess onward, and I'm getting bored of the franchise (I didn't like BotW either). So, there are only a few franchises I'm interested to, and some of them are dead (such as Warioland and F-Zero).
This seems sad and all, but trust me, Videogames aren't all, I've better stuff to do, so if I don't get the games I like, I just don't play or play different stuff, or either I can do retrogaming, nobody is stopping me from playing the old games I acually like once again. I'm not forced to play a game I have 0 interest in, only because its main character has been added in Smash.
The point is, all this focus on third parties and games I have zero interest in, is making me losing interest in Smash as a whole. Add the fact that I don't like many aspects of the post-brawl (including Brawl) Smash games, the focus on grinding collectables (stickers, mii costumes, spirits) and the countless missed opportunities each game has, along with the gameplay that didn't change much and still has the overall mechanics of Melee (casually speaking), and the fact that the movesets stopped being creative time ago.
My bound with the Smash franchise is very weak, I used to be a big fan of the series, but it seems the series is not for me anymore.
The same reason for why I never got into Playstation All Stars Battle Royale, because I simply don't care of its content. Smash is becoming the same thing for me.
I had the chance to play some Brawlout time ago... it's a Smash clone, with a slighty simpler gameplay (less moves) but still decent, and has a couple of crossover characters (Yooka Layle, the Guacamelee guy, and another from Dead Cells). I played Guacamelee and I didn't like it much, I never played the other games. Brawlout feels exactly like Smash Ultimate to me: it's a platformer fighter filled with characters and content I have 0 interest in. The gameplay is decent enough and can be fun, and some movesets are even a bit interesting, such as how you can create ice platforms in the air and play a drum to summon thunders, and stuff. It's allright but not something I would spend my money into. I feel the same about Ultimate so far. Maybe if there was some big innovation in gameplay...
If I got one of my favorites as DLC maybe I would decide to get the game, but even in that case, it would be just for the character, it wouldn't change my opinion on the game and the series overall... but at least Nintendo would sell an additional copy I guess, for what's worth.
Don't get me wrong, I still like Smash (else I wouldn't be here), I still would like to get a new Smash game... it's just that Ultimate is not the game for me... maybe I'll be more lucky the next time, especially if there's a reboot, and even more especially if Sakurai is not the director anymore and some new guy takes over the series.