Maybe I have a lack of imagination, but what on earth could possibly be the failure modes of floor tile?
The problem with ground coverings is that you generally expect it to be reliable and consistent if it looks like it should be. A single loose, chipped or cracked tile might be worse than an entire floor of them.
http://www.certainteedshinglesettlement.com/
I would imagine the failure modes are similar. They are marketed and guaranteed for 30 years, you actually get like 5 years, whoops.