I actually wouldn't even mind them holding off Brock-Roman for WM33, provided they were able to get Roman Reigns so red hot by then that there wouldn't be resentment over him beating Brock. That would require him to have a suitable opponent in the meantime though, and HHH is not really that guy, at least not for Wrestlemania.
The reason I am fine with them postponing Brock-Roman as long as possible is that after Brock does his first real job since ending the streak, I feel like he's going to take a hit in terms of his value. He'll still be valuable, but it will take something out of him. So the longer they can put that match off -- time also allows them to heat Roman Reigns up significantly -- the better.