I tend to share Daddio's pain. In our PTO, there are certain members who respond to every single suggestion with "But we've always done it that way" or "But we've never done that before." In the process, they make it clear to new members that their ideas and opinions are not welcome, and sure enough, those new people don't keep trying for long.
There's got to be a balance between sticking to what works so you're not constantly reinventing the wheel and getting so mired in "the way we've always done it" that no new ideas can be heard.
Personally, I'm a big fan of explanations along the lines of "because if we don't do such-and-such, thus-and-so happens." It helps if you have notebooks for each officer or committee chair so those people can see why certain things were set up the way they were and what problems have been experienced--and hopefully solved--in the past.
If you want to change something and have a valid reason to do so (obviously change for its own sake is a waste of everyone's time), persist in stating your reasons and ask those who don't want to change it to do the same.
It if is not broke, don't fix it. I know everyone wants to make positive changes when they come on board. My biggest pet peeve is why does everything have to change? As in any business, just because you may be new in a job doesn't mean you rework the entire company because you are new. Somethings just don't need to be changed and I find that that is usually how things go haywire. There are some things, such as the way you do your budget for example, that actually work.
Daddio, you should leave it alone if it is working and has been working all those years. Heck, when I was President of my organization, lots of things worked just fine and we left it that way. Sure we added some things and deleted a few things to keep things "fresh", but the organizational procedures stayed put.
How do you change the way something has always been done? I'm in my second year as pres, and am making progress, but somethings (such as how we do budget and what it is spent on) has worked for 23 years so we are not suppose to touch it.