How could anyone with a functioning heart possibly hate on Isabelle? Look at her!
Many different factors, sometimes even a combination of a few
-Isabelle is a cutesy character
-smash wasn't the focus of the reveal
-"weak" reveal that didn't inspire hype reactions
-some expected different characters because of certain leaks
-she's a unique character instead of an echo
-Isabelle isn't seen as important (I think some people didn't realize how huge she actually is)
-the delayed of the Direct seemed to have raised expectations even further then usual for a direct. I swear. I mention I felt Smash would not be a big focus and have at most one reveal.
Plus a few more. Tho to be fair, there seems to be a more positive reception then the negative loud minority.