Just
whoever designed the bolts to go through the mount needs a slap.
Support the engine with a jack and its no bother to remove.
It acts as both a support and a ground for the starter armature (Or at least I think so)
I must admit i've never heard that before 
Its from experience. I've replaced 2x starters in MK2's and in both cases, the new starter performed exactly like the old [assumed faulty] one. But after replacing the bell housing bush, they worked just like new.
@mongchops ... just change the bell housing bush and report back, seriously. It takes minutes to remove, just use a suitable sized tap and thread it into the bush, then pull out.