It's called "discernment". I don't buy junk just because a classic character's face is plastered on it. As for Kermit's attitude...I think the phrase "it's getting old" is the appropriate one here. For me, it's "been there, seen that". And I don't think I'm alone in that attitude. Given the Muppets' lack of appeal to today's audience, it should be clear that the old, much-used material isn't working (which no doubt is the reason the Muppets are getting thrown out of Disneyland - their attraction wasn't drawing enough of a crowd).
Besides, Kermit blows hot and cold when it comes to Piggy, and that's where it gets irritating. In the old eps he is indeed abusive at times, yet in the movies he's amorous, and in interviews he's all over the place. So you wind up with viewers not knowing what to think and finally deciding it's hardly worth the trouble. Then you have more people losing interest. It's a self-destructive cycle IMO.
I remain convinced that the people behind the Muppets nowadays don't know what they're doing, and that Disney would be best served selling them off and using the money for better projects. JMHO.