The bell is what really helps define a trumpet sound... For instance the Bach Strad you have there has bells 37, 43, 72, (65, 25, 38) and this is just Bb from just Bach.
(Correct me on this) but some people speculate that some of those legendary Committee trumpets were amazing because (in part) of the bell taper.
I'd like to think that it affected your tone in some way or another, but not in a way that you'd notice. I don't know.
Go get it fixed...?