There are 300SL replicas available (not that Mercedes-Benz likes the fact), and it seems to me that if Chip Foose wanted to put his world-class skills behind hot-rodding a 300SL, he might better have considered starting with one of those. Then again, it was actually the client's car (BASF), not his . . . He just gave the client what they asked - and paid - for. So, shame on BASF.
As for the 300SL being "no Da Vinci to begin with" . . . Well, we are all certainly entitled to our own opinions but I doubt that one would get a lot of support from automobile afficianados. A 300SL is pretty universally recognized as a work of art, even if it isn't everyone's particular cup of tea. While it's tempting to say "To each their own", or to point out that you can do whatever you want to your own car . . . The reality is that current owners of certain cars are custodians of that car for future generations. They do have a certain responsibility.
Fortunately, it doesn't look like any of Foose's work is irreversible. Personally, I don't think the work that was done enhances the car at all. I would be willing to predict thay someday, someone will restore the car correctly.