I guess it is no different than Super Mario Bros. 2 or Zelda 2, different is not always bad.
I got TJ&E 2 and Sonic 2 for my birthday and those were the first two games I got. But my sisters and all my friends also agreed with me it was a lot of fun. I had one friend who had the first game and I would go to his house and play it because I liked the one I had so I expected it to be as good and it was this awkward and weird game that just was the slowest thing ever on a system that prided itself on lightning fast game play.
Mario Sunshine is not even a Mario game and yet people love that game so no I don't think that matters, gameplay evolves. Why I liked the second one was because it was so colorful and the humor was just right up my alley. I liked the story, the characters, for a platformer it had a really unique combat system instead of popping enemies on the head you trapped them in jars, the aliens were super funny, the funk powers were all useful and there are parts where you really have to plan your fun moves just right to get through. The music is top notch and the mini games are better than the ones on the first game too.
I can understand why those who played the first enjoy it, it was a unique experience but I think they let that blind them to how great the sequel is because they just can't accept change.