Well, it really depends on the fragility.
I mean, you could go out and fire a $100,000 Luger P-08 or a $250,000 Winchester M1873 and really, as long as it'd been fired before, that wouldn't really hurt the value.
But if you have something that could easily be destroyed by a slight ding or a tear (art on paper, textile artifacts, porcelain, etc) then really it may be too risky to take it out and about, or to even use it as originally intended.
I don't think it's necessarily about the dollar amount, as much as the scarcity and sturdiness.
-K
p.s.- So, regarding the violin, it'd be foolish to take it camping, but as long as one is careful, I think playing it in church is a wonderful use of a terrific instrument. Art hangs on walls, instruments are to be used.