There alot of those "are they necessary?" prefixes around. But isn't "ver" the same as "for", which I imagine is the same as "pro" from latin. Meaning either "before" or "causing" or "facilitating" or similar.
verstehen, vergehen (active), vergehen (passive), verdammen, verabreden, verfahren, verlaufen, verfestigen, verändern, verallgemeinern, veranschaulichen, veranlassen (ver+an+lassen), verlassen, verärgern, verarmen, verbiegen, verdrehen, ...
It's hard to grasp, but I think "ver" has some subliminal meaning. The "ver" words feel different than their synonyms.
It can be broken down to 8 different cases according to Duden and there is actually some logic behind it (though not the best and most consistent :D).
The (I think most common) word for 'understand' in Japanese translates to something like 'it resolved for me'.