I think some of the anti-Catholic bigots who disparage and deprecate Mary so obsessively are actually intimidated by her example and need to tear her down to avoid feeling so bad about themselves.
Others are mislead by anti-Scriptural lies like "sola scriptura," "sola fide" and "sola Machen."
Unmitigated hogwash all over again.
No, I think they really believe these things, but it is certainly the enemy that tries to decieve people into beleiving that Jesus could be jealous of his loving mother, or that our love of all things associated with God is somehow evil. There is also the problem that sometimes much of our practices are done more out of tradition and the original Love quotient isn't experienced by some Catholics in name only.
Catholics have been given so many wonderfull gifts from God and many of us our like spoiled brats who completely take them for granted. I know I did, I certainly appreciate and understand things so much better now. My Protestant convert friends are some of the best Catholics. They appreciate God's gifts more than some of us who have always had them.
I think it's because any time a Catholic does something undeniably righteous, it is a witness against their unbelief.
Remember Korah is a model of apostasy, and his sin was to despise the authority of Moses.