Eh, I get your point, but they are new games in the series, not the EXACT same game.
I guess I have to ask how you draw that line of distinction, then. For the most part, you've got the same, basic gameplay from one platformer to the next, with characters and graphics the only meaningful changes.
Kart and
Smash change the characters and tracks, but it's still the same core game, and neither is deep enough to say that the current one feels differently than the last.
On the flip side of that, I'd say that
Halo has done an awesome job at trying new things and keeping iterations from feeling too redundant. That could mean the additions of LIVE multiplayer and dual-wielding in
Halo 2 (and don't forget playing as the Arbiter), the addition of equipment in
Halo 3, Firefight's implementation in
ODST,
Reach's addition of Armor Abilities and a campaign that's more personal to the player, or
Halo 4's addition of Ordinance, a BUNCH of game types (I still hate that
TMCC doesn't have Regicide), Loadouts, a new enemy/weapon class (Promethean), and then you have
Halo 5 adding things like squad-based, seamless campaign play, the Warzone game type (which, despite the dirty pay-to-win, is conceptually cool), and a host of new features and abilities that I can say from playing in the beta make you react quite differently in multiplayer (a major example being that in
5, your shield wont' recharge while you sprint, making learning things like dodging and taking cover even more crucial).
Heck, if you touch
CoD, I'd even say IT changes things up more than something like
Kart or
Smash. Play
MW2, then
BO2, then
AW. They'll feel SO much different from one another.
Forza even tries it with the trading off of
Motorsport and
Horizon, and
FM6's additions of night and rain racing, along with IndyCar events (seriously, they're freaking cool) gives you a lot of different experiences within a franchise that we can all admit gets updated too frequently.
I'm just saying, I'd like some examples to defend that idea. How do
Kart and
Smash really differ from one game to the next? How is
NSMBU different from
SLU, and how do THEY really differ from the iteration on the Wii? How about the
Pokemon games, where you get "new" things like double- and triple-battles? I feel like Nintendo's the one surviving on brand names and redundancy more, not that I don't like
Kart and
Smash on my Wii U, and you can bet I'll be all over
Woolly World in a couple of weeks.