The content and presentation values are wild but the core game play is increasingly more YMMV with every entry since Brawl. It's the epitome of the kitchen sink kind of design where the team throws everything and then some into the mix. When you see all of the loving detail that goes into character modeling, the things referenced, the art direction and sound composition, you can tell that the team really went above and beyond for the sake of representing entire eras of Nintendo's franchise history. At the same time however, the core gameplay, the main draw to the series, is trending away from the universal things that made previous titles enjoyable for everyone in the hopes of retaining or grabbing an audience that was always going to show up to smack Kirby and Metroid around with a paper fan (RIP paper fan by the way).
People eat up the extra content and things like the bonus modes and grinds for stuff like trophies, custom moves and gear for their Miis and wouldn't really care about finer mechanics in matches as long as there are platforms, Nintendo characters and the goal is still to get the ring out.