potential damage from such obstructions as high pavement edges...They are particularly helpful in protecting a lowered car.
That's an interesting point. Usually when parking against a kerb I drive until I feel the tyres nudge the kerb so that the nose or rear overhangs the pavement. My car isn't lowered, but I do wonder if it was would I be unable to park in the manner I'm accustomed to. Is this what you lowered folk have to deal with? If so it sounds fairly impractical. 
....Indeed it is what we have to deal with and IMO worth the compromise for what a great handling setup (more than just lowering a car) brings to the joy of driving. I don't go into multi storey car parks with ramps either.
In my case I need to protect a real carbonfibre exhaust trim around custom black ceramic quad tips < It costs a lot of money to look this cheap!
Btw, at the risk of sounding pedantic, I don't think it's technically legal to park so that any part of your vehicle overhangs, and therefore can be termed as obstructs, a pedestrian pavement. I'm not trying to get at you but personally I don't think it's a good practice. [I've probably been spending too much time recently chatting to high flying lawyers!]
