Do you honestly think that's not a terrible idea? Replacing your company website with a wiki?
Maybe there's a tiny minority of companies for which that would work -- they'd be small, obscure, have a loyal fanbase, and almost never piss anyone off. For anyone else it's a disaster -- all you need is one disgruntled customer (or fanboy for the competition) with too much time on his hands.
It's not just the "control content from one bad seed" issue. Wikis are great to solve some problems, deliver some content, etc, but they're not the answer for everyone. There are different levels of transparency for us to explore...
Maybe there's a tiny minority of companies for which that would work -- they'd be small, obscure, have a loyal fanbase, and almost never piss anyone off. For anyone else it's a disaster -- all you need is one disgruntled customer (or fanboy for the competition) with too much time on his hands.