[nrinaudo]

I agree with part of your sentence only. Managers, especially professional ones (as opposed to ones that were promoted from the kind of position they end up managing) do tend to push for client-facing features with little thought to the accumulating technical debt.

It's been my experience, however, that when left to their own devices, developers tend to either learn new things or refactor code that's getting too hard to maintain. And both are important, critical even, but certainly no help in getting up to date documentation, fixing "painful" bugs, or writing good tests. In fact, they can even be counter-productive in that respect: heavily refactored code will invalidate at least part of its documentation and tests.