2) It is one more run through/competition, it's not adding month on to a season. It is one more "weekend" for a handful of bands in the state. Just because you are lazy and don't want to do it, that is on you. If your district/community will "not allow" you to opt out then maybe there is a reason for that. The support/excitement for your program would be great.
3) Several 1A programs are now thriving because of their state contest runs, just a few short years ago many of them were barely able to pull off a 3 at marching contest and now they have great band programs. Competition breeds success/support.
4) Many bands go to state without props/custom shows. Look it up, especially at the smaller school level. Many bands do not have custom shows and have limited if any props. I have been to state 2 times now and have done so on Stock Music and minimal props.
This is all just my two cents - the more exposure we give our band programs, the better off we are. This is the USA where we VALUE competition. This dreamland where people are all of the sudden going to wake up and overwhelmingly support the arts is not going to happen. Besides, OAP has state every year ...