Almost all the art in our home is from local artist and almost none of it is framed. Several pieces wouldn't want to be framed at least one is too heavy to frame. Most of the art in frames is stuff that we inherited and isn't local.
I too have some art from one of our local creative minds. I once asked him how he would display the prints I was purchasing.. He actually recommended frameless displays. I don’t think he saw frames as a part of his work at all. I guess it depends on the intention of the artist. Most of the pieces I like to see framed are pictures I have taken, but one of my favorites exists as a border-less canvas on a hidden frame.
It's not like an oil paint on canvas that no one ever touches is in any dire danger. So no, we don't really do anything to protect it. I suppose a big earthquake might smash stuff up but at that point the art would be the least of our concern. We have a big geometric cut glass piece that is embedded on a piece of half inch lumber. If it ever crashes down I hope no one is standing under it, I worry about the floor. It's super heavy and mounted into the wall studs. I love it enough that I was willing to deal with it's weight. I don't think it's practically protectable but it might be in less peril than that which is under it. There is a small painting on a wood substrate that has some kind if shiny shellac over it. Your question makes me wonder if it should be framed because I could see it getting chipped if it fell but I think a frame might detract from the piece, I'm pretty sure the artist intended it to be displayed without a frame.