Devil's advocate here, but how are skin color and body size any different from eye color or height preference?
The only way to do it truly fairly is to disallow any physical characteristics. By only blocking some you just change the criteria/groups who are discriminated against. But who would use a dating site where you have no idea what the other person looks like?
Better to use statistics to level the playing field by, for example, showing people with less % likes more often. This is pretty much how affirmative action works. Give people biased against by other humans more opportunity to make up for it. Lot easier than trying to fix the bias in the humans.
If you think you can make humans ignore their sexual preferences by hiding certain identifiers you're a lot more optimistic about humanity than I am. I expect the most popular openers on the site to be "r u fat?" for men and "r u at least 5' 10"?" for women. Isn't it just better if those people never talk to each other in the first place at that point?