Flash certainly became broadly hated. It had a pretty long stretch of being loved, and enabling content that was loved, though. Up until about 2005 or so, flash was critical tech for the young web. By 2010 it was clearly heading toward an end.

I remember strongly disliking Flash before 2005, and many tech-minded people I talked to agreed. It was an awful install, always needed an updated, was a memory hog, and was a pain in the ass to use without it crashing. Yes, it must have been great to create apps with (I never did), but it was not beloved. Flash games were beloved, not Flash.