It is paganism that I consider to be the derogatory and misleading word. Calling it paganism was and is a vile attempt to suppress the local religions, whether you consider them derived from PIE or not.

Yes, they were not not overarching, mandatory systems of belief, but is not an excuse to dismiss them as religions. The religions were real. After all, we see the same continuing religious beliefs that you noted (sacrifices, festivals, veneration, etc.) in Hinduism, which traces a direct chain to the PIE religion.