I go with most of the above.

But the overriding issue for me has to be general discomfort much of the time. I need undergear that supports me otherwise I very quickly get a bad ache in the groin. At the same time I need extra room in the crotch area otherwise I get a different sort of pain.

My solution (custom made jockstraps) works pretty well but it can feel uncomfortable especially when the hot weather comes as now.

Edit:

There are occasions when certain activities can be hampered by being over-endowed. Cycling is one for me .. see this very ancient thread: Saddle Sore