I mean in general, that's the thing for the popular franchises. People will complain, and still buy the games.
Also, if we turn our focus away from the naysayers for a moment, and focus on reality:
What franchise spans across 20 years with over a thousand characters in 3D models, and all still fully usable, and releases on a yearly to biennial schedules? You're probably going to have to cut down at least one of those aspects eventually..
On comparison I heard is Yokai Watch, and I was told they don't really carry forward all their creatures into the next installment..
Anyhow, I'm not going to disagree with which one aspect to cut down on, but the point is they chose to cut down one, and the act of cutting down something makes sense.