The weather was surely the crucial factor, not only the cold at Christmas but the rain (for various technical reasons the industrial revolution tended to happen in regions of high rainfall). Reed instrumets are much more susceptible to wet, both reeds and the key mechanisms. Also the volume factor ruled out fiddles, you get a helluva lot more bangs per buck from a trumpet. Another factor was the needto have lots of musicians (it was a very collective activity). They wouldnt all have verygood ears, and the good thing about the valve mechanism is that once the instrument is tuned (the bandmaster can do that) it tends to come out not too bad whover plays it. The formalised competitive structure resulted in standardised instrumentation, which put paid to most of th bands with irregular lineups including reeds, alas because I'm sure they weremore interesting (to my ears anyway). I remember playing lot of carnivals in the Rossendale area in the 80's with a street band (of the more modern alternative style), and there was still one band going with all the discipline and uniforms etc of a brass band, but it had clarinets(and maybe a couple of saxes). Ithought it sounded great, and surprisingly unlike a military band even though it had the same lineup. I think it was from Todmorden, dontknow if its still going.