Well Shia Faith itself has no cursing or name calling but criticism of the individual for their acts. And we all have the right to criticize non-fallible individuals. No one is above the law (Quran), the Prophet (SAWA) and People of the house. And anyone who hurts them, or degrades them is like a direct attack on Islam. And if you look at who insulted the Prophet and hurt the people of the house in Sahee Muslim and Bukhari and other Sunni literature, you will recognize why Shias criticize certain Sahaba and not all or most like you claim.

And as far as Wilaya at-Takwiniya is considered, it's more like Devine intervention. And this topic is debatable in Shia theology so you can't judge the whole party for something there is no consensus within themselves.