Like others have said, companies will make whatever they feel they can sell/people will buy, hence the 'shoe' style riding 'boots'. I normally go by the fact that if the pros at MotoGP wouldn't be caught dead wearing something, then it's likely made more for image than actual protection from a crash/slide (with the exception of various armour products more suited to an impact on the road vs a slide on a track).
Also to add I just picked up a pair of Alpinestar Supertech Rs from GP Bikes and love them, although I haven't had a chance to try them on the bike yet. I almost bought the SMX+ instead, however I wanted the additional ankle protection of the Supertechs, plus I didn't like the closure system on the SMX+ at all as the zipper felt like it could rip over time.
Those guys ride 100+mph consistently. I'm sure you do not need protection they need doing the speed limit. But hey I'd rather be over protected then under.
I bought shoes for when I have jeans on with my knee guards. If I have my boots on my knee guards won't fit. I only really use my boots for when I have me 2 piece leathers.