It can be very useful to have a big tube amp when you are playing outside and the sound man working the PA doesn't give a shi# about your sound and he keeps turning you down. You can turn up your amp and get to where you want to be.

Also, you may "need" a big amp to drownd out a belligerent loud drummer. You also might be in a super loud band - the house is not going to let you blow up their expensive PA, as has happened many a time.

A big amp isn't for everything, absolutely, but it is sure fun to crank one up once in a while and really roar, if only for your own pleasure.

And believe it that Bonamassa has his reasons for needing big amps; like Deeaa was saying, and so on.