1) Drain protectors need to be both easy and un-yucky to clean, and work well to keep gunk out of the drain.
2) Drain protectors seem like they should be a natural or included part of every sink. My stylist described a type of permanent drain protector that screwed into the drain, and I kind of knew what she was talking about, or have seen versions of what she described. However, she said that drain protector didn't work very well and wasn't practical. It needs to be simple a la Occam's razor.
3) This seems to be a product that people shouldn't have to think about, it should just work. I think that it is not in the interest of drain makers, however, to keep things from clogging the drain. Drain makers sell more drains if they get used and clogged, right? What incentive does the market have to fix this problem?