I fully understand the idea about motivation (and my "let's muddle through"-oriented brain is always tempted by this), but I think it goes both ways:

If it takes short to refactor the program but, because of the lack of safety checks, what seemed to be working "in some limited way" turns out to be a big ball of bug-ridden mud in the end, and maybe the whole approach wasn't sound, wouldn't that also kill motivation for future refactors? And what if keeping the motivation high for the more impulsive programmers leads to worse software?

Doesn't this look like something analogous to the old carpenter's motto: measure twice and cut once? "But I don't want to measure, I want to cut it now, it'll be faster! Measuring kills my motivation!" :)