If my work ever makes it into a museum, I'll let them decide how to mount it. I don't think museums choose works to purchase or display based on mounting practices. They tend to look for other qualities instead, like cultural importance. For instance, a poorly mounted photo by Edward Weston has a much better chance of making it into their collection than any of my work mounted in the best possible fashion.
As for galleries, I don't think they care, so long as it's sells quickly. They're in the business of making money, not preserving art. All of the galleries that I've sold my work through basically have the same attitude:
"How much space is it going to take up? How much do you want for this piece? How long does your work usually take to sell? How's your online presence? Do you have something cheaper you can sell as well, because most people don't come in here to spend a ton of money? Do you know this guy? He can put your image on a coffee mug and those tend to sell pretty quickly. We've got a showing for another artist this weekend, can you make it out to that? At least send out some Tweets and Facebook/Instagram posts promoting it. Also there's some really good stuff in the back that I think you may want to buy, have you seen it?"
They're not so much concerned with art as they are with profit. And that makes sense for them. Galleries around here usually don't last long unless they're owned by someone who doesn't need the money, and uses it primarily as a platform to be a part of the scene.