Probably because most plugs are VST compatible in the first place. It's only been in the last 12-24 months that most companies are actually supporting RTAS as well as the VST and DX formats.

I was just reading about one last night when I was looking around the internet. I'm afraid I can't remember who makes it, but I think I was looking around that kvr website or whatever it is called.
Sorry I can't be of more help :(

Saw a thread that was joined by the developer of the VST to RTAS converter.

He stated that Digidesign commissioned his product, but that part of his agreement was that he could not do a RTAS to VST product.

Digidesign owns the RTAS standard, and control it with an iron fist.
8)

Oh yeah, I read that first post wrong. RTAS to VST is useless. I was thinking VST to RTAS.

Well, i wouldn't say useless. The biggest if not only thing i would get a RTAS - VST wrapper for is Voc-A-Lign.