Alan Kay famously went through several iterations of rewriting the first Smalltalks from scratch and he is a big believer in that approach. I don't know if it's easy to find him talk about that explicitly but here's one example:

http://queue.acm.org/detail.cfm?id=1039523

> AK I had the world’s greatest group [in the Smalltalk era], and I should have made the world’s two greatest groups. I didn’t realize there are benefits to having real implementers and real users, and there are benefits to starting from scratch every few months.

I'd recommend his talks at OOPSLA or anything you can find on YouTube. Especially 'The Computer Revolution Hasn't Happened Yet' is a gospel for contrarians.