I just had a black backsplash installed and I spray painted our switchplates (not the switches themselves) black. They make it look much nice and almost invisible. You can buy ones that are "paintable" for about $6 or $7 each but it was much cheaper just to scuff up and spray paint the ones I have. If you are buying new ones they have ones with invisible screws.

Get what you like and don't worry about what someone else might think, esp. in 10 years! You can always change it. I just bought a new house and in the model homes, they have the black as an upgraded option. A lot of people like it.

Haha, we have an older house where the original switches and outlets are black. I got white plates exactly like the one you show. I kinda dig the look.

I would not draw any attention to items that are utilitarian. These are not decorative wall decor. When they end up on walls that have wallpaper or tile backsplash, I think it's nice to match the background so they blend in.

The ones in my kitchen are all stainless steel. It depends on the room.

IMO these are not a decor item and should be as invisible as possible. I use LUtron since they have so many colors to work and I like that the switches themselves are also the same color and can be changed when you change the wall color. The next best is paintable the same as the walls.