It isn't a horrible idea. Using a ready made framework all the time without regard if it's right for the job is a horrible idea.
For some apps which have a certain level of complexity and require some extra flexibility, you end up wasting more time fighting the framework than getting the job done.
It helps if you have a well defined standard in place, for python, that means WSGI. Coupled with good libraries, it's hard to beat.
Right, but that's not "writing a framework", it's "using existing libraries in conjunction with one another". There's no real "magic", directory layout rules, etc.
Maybe you end up writing a couple scripts to tie them together or something, but it's hardly a framework. And in many cases, yes, it is a better choice than a framework. And still a better choice than writing your own framework.
For some apps which have a certain level of complexity and require some extra flexibility, you end up wasting more time fighting the framework than getting the job done.
It helps if you have a well defined standard in place, for python, that means WSGI. Coupled with good libraries, it's hard to beat.