Some former Catholics are very bitter about their having belonged to the church, for several reasons.
One, Catholics don't (usually) go as far as Jehovah's witnesses in making you swallow the faith, but they used to. Some people remember their childhood as a terrible thing.
As you can imagine, those who had the horrible experience of being raped by a priest who was later helped by the Church are not very happy about it.
Some other Catholics, usually the ones who didn't really behave, find themselves in situations they don't like and go the fundamentalist way. These ones are very bitter about their having been Catholics, but I'm afraid the reasons are not theological at all. It's just that they want to feel they are better now.
Some former Catholics get elected as presidents (or important members of a party) and they do want to destroy the Catholic Church. Again, the reason is not theological; it's just that the church is another enemy. This happens where the Church was very much instrumental in mantaining the establishment in place, such as Mexico and Spain. Maybe Italy would be in this situation as well. Castro very much succeeded; he almost wiped the Catholic Church out of Cuba.
And some former Catholics become atheists and then they want the Church to end, but usually through non-violent mechanisms. They just want the people to stop believing.
That said, I may be wrong but I don't think there are many fora like this one against the Catholic Church. You do undergo stuff, but it is usually not as serious as you do under the witnesses. The only exception, to my knowledge, is found in the (former) members of the Opus Dei, which a good number of Catholics consider crazy (I mean, the Opus Dei). I find the Opus Dei very much like the Watchtower in terms of its control of people.
The Catholic Church has a much longer history and a more variegated record of getting involved in worldly affairs. Some people cordially hate it, most others don't, really. Except perhaps for JW's.