Musicbrainz has no problems with characters like ?&'. and so on. The str...

...ipping of these characters is unnecessary and it even caused problems when albums or artists made use of these characters.

Here are two examples where problems occurred:
With stripping:
http://musicbrainz.org/search?query=%22Outlaw+gentlemen++shady+ladies%22+AND+artist:%22Volbeat%22&type=release
No results
Without stripping:
http://musicbrainz.org/search?query=%22Outlaw+gentlemen+%26+shady+ladies%22+AND+artist:%22Volbeat%22&type=release
Three results

Messed a bit with a less literal search too, but that isn't needed in my opinion.