Cases are what wear. The big bearring wobbles out the race, but still the cause is the crank out of clock or whatever its called. Some call it trueing the crank, but from what I understand from previous posts, assembling the crank right, reduces vibration in a certain rpm range, but is never truely "balanced" And it was also mentioned the the majority of cranks are out. Check out Stewarts Crank Press Thread. You think all engine shops have one of those? Think he and his Dad made that for a good reason? I think it is a big deal, but not an easy fix.
Handlebars and rubber mounting helps symptoms, not the cause. Cases are too expensive.