Mamasperspective
If you treat your DIL as 'less' or like she doesn't matter, it can potentially cause distance between you and your son (this is the woman he loves more than anyone else in the world) and also, may very well come back to haunt you if they have children together
Quite true. By nature of it all your daughter in law or son in law are the most cherished person to your son or daughter. So by extension, should they not be treasured and valued to you as well? When my oldest son was a small boy he had a stuffed dog he was mad for. I didn’t espixslly love the toy, as it was old and dingy and not my taste. However he thought it to be a treasure beyond all others and so over the years I went to great lengths to look after, gently wash and be sure to never ever misplace it! It was the thing he loved most in the world and as such I cared very much what became of it. Likewise with my adult children’s chosen partners. Perhaps a poor analogy as of course none of my sil or dils are “old or dingy” , quite the opposite they’re lovely people , but just as my son loved that stuffed dog, even if they weren’t lovely I would love, and treasure, and want to celebrate them , simply because they mean so much to my grown children.