"Playstyle" and "character" are synonyms. Your "character" in a competitive fighting game is a core set of attack properties and physical attributes. Things like how they look or what game they're originally from are just window dressing; in all the ways that matter, Mii Brawler, Mii Swordsman, and Mii Gunner are as unique of characters from each other as Mario, Link, and Pikachu. Even if you did care about aesthetics, they're pretty different anyway. Mii Gunner is missing his forearm and instead has a large gun while Mii Swordsman has his full arm but also has a huge sword. That's a bigger aesthetic difference to me than Link and Toon Link have or than Fox and Falco have for that matter. Given the obvious that Link, Toon Link, Fox, and Falco are four different characters, how is it not equally obvious that Mii Brawler, Mii Swordsman, and Mii Gunner are three unique characters? I hope the character select screen, which has in the past also tied together Samus and Zero Suit Samus, is not considered important here...
That being said, I totally don't get why people are bothered by these three getting focus. E3 revealed five newcomers. We've actually received about an equal amount of information on all of them with Mii Brawler actually probably being the loser from the five. All five E3 newcomers look pretty interesting to me, and given that the five of them are collectively unknowns at this point far moreso than any other revealed characters, I don't see how posts about any of them are unwelcome. Today's picture in particular was a stage picture about a stage we previously knew very little about with the Mii being a largely tangential inclusion to it (probably because, you know, it's his stage) so I don't even know why dissatisfaction over Mii pictures is the topic tonight.