Completely agree. Some of the most literate, easy to comprehend and maintain, stateful, Gui-heavy desktop apps I've written / worked on have been detailed mode

Completely agree. Some of the most literate, easy to comprehend and maintain, stateful, Gui-heavy desktop apps I've written / worked on have been detailed models of interactive objects, because it was appropriate for the problem. In other problems (the classic web, data processing), it doesn't make as much sense to hydrate this huge, complex ecosystem of objects over and over just to throw it away again, or to end up with functions which are nonsensically bound to what is really just a data structure. Other operations are particularly recursive or parallel by nature and lend themselves to FP at least in part because of the work done in the FP community to handle those paradigms extremely well.