There is also the argument that Flash is simply another form of animation, like stop-motion or cut-out or whatever and should be taken on its own with its own positives and negatives.
This is a view I would be inclined to support. After all, you can't get the same things in cut-out animation that you can get from traditional hand-drawn animation but that doesn't mean cut-out animation doesn't have merit or isn't valid. Cut-out animation brings its own character and can be really entertaining - just look at Terry Gilliam's Monty Python work.
Similarly, Flash has its own limits and should be taken on its own... right?
Well, the problem here is that Flash is being used as a direct replacement for 2D. It's faux 2D. If anything, a huge amount of studios using Flash are trying to fool you into thinking it's not Flash because Flash was a dirty word for a while in the industry - not so much now. If Flash is being used as faux 2D, then it should stand up to direct comparisons.
But it doesn't.