Smash 4's base roster was a direct response to many of Brawl's criticisms. The biggest criticism when Brawl was that there were very few new first party franchises. Two of them were retro franchises (Kid Icarus and R.O,B.) and Wario, while unique, was still tied to Mario (and was often seen as a Mario character like Yoshi.). Pikmin was the only completely new first party franchise that was included that wasn't tied to the NES. People were expecting a lot more new franchises. In hindsight, it made sense, Melee had only given us three new franchises period (Ice Climber, Fire Emblem and Game & Watch), but people still felt like Smash wasn't including enough first party franchises. The only third parties being Sonic and Metal Gear also drew some ire. When people learned that third party characters were on the table, they went wild. Fan rosters had a ton of them, and even conservative rosters usually gave us around four or five third party franchises.
So, Smash 4 gave us...
- Animal Crossing
- Mega Man
- Wii Fit
- Punch Out!!
- Mii
- Pac-Man
- Xenoblade Chronicles
- Duck Hunt
That means we got 8 new franchises, 6 of which being first party franchises. Animal Crossing, Mii and Wii Fit were juggernauts. Punch Out!! had been requested for ages. Xenoblade Chronicles was a modern critical darling. Duck Hunt was the most financially successful and recognizable retro pick. And I don't even need to explain Mega Man and Pac-Man.
- Street Fighter
- Final Fantasy
- Bayonetta
Then DLC went an added three more, making the total amount of franchises 11. Two giant franchises and a modern critical darling. Smash 4 introduced more franchises than any other Smash game. Even the original and Ultimate (after DLC) only introduced 10 each. So that's one major criticism directly addressed.
The characters from already represented franchises were great picks as well. Rosalina, Greninja, Palutena, Robin and Bowser Jr. were all popular characters then and remain popular characters. I think a lot of the issues some people took with them was that they were accuses of being "flash in the pans" or "corporate picks that no one actually wanted." Almost ten years later and no one would claim that those five characters aren't popular and beloved in their franchises, at least objectively. People are just really bad at figuring out what's genuinely popular and what's a trend. And some of those negative first impressions can stick around. Lucina and Dark Pit got in by different circumstance, but they were still popular characters. The only potential dud of a unique character was Corrin, even then, they aren't hated nearly as much as some people would have you believe.
Smash 4 was a game of pushing boundaries and introducing new ideas. I keep seeing people state that Smash 4's roster was bad. I heavily disagree. I just think that some people felt left behind by a change in direction. One of the reasons Brawl's inclusions were so celebrated was because the roster focused on building up what was already there. Smash 4's didn't, it focused on bringing new things in. If you didn't feel particularly strong about the new franchises, it could seem lame. But that's where I recommend you try something new. Smash 4 got me to try Xenoblade Chronicles, Final Fantasy and Bayonetta. I love those games now. It was incredible to see Punch Out!! and Fire Emblem Awakening get a character because I loved those games. Without the Smash 4 additions, the roster would have a lot of major holes, and part of the reason that Ultimate's roster is so incredible is that it has the Smash 4 characters in it.
Gameplay is another matter, but that's a gameplay criticism, not a roster criticism. LMAO