To be honest farmpony, I think it's a fad.
The boots are designed to absorb shock and to prevent any harsh movements from causing pulled tendons and ligaments and muscles.
I use my boots only when I am doing CC or Jumping. I never use boots when I am doing flat work - and you are right farmpony, if you don't need them, don't use them.
These boots are wonderful and they do their job, but don't become too dependant on them, especially when you are doing flat work.
If you do choose to use them, make sure they are on your horses legs no longer than 2 hours. They are thick, 3 layers of neoprene thick and don't breathe well.
That goes for any boot lined with neoprene *which is pretty much the majority that are out there* because you can cause damage if they are left on too long due to the heat that they create between the leg and the boot.
My personal opinion, don't use the boots for flat work - but that's my choice.
And no, your horse wont become dependant on them at all if you use them all the time. What you do want though, is for your horse to beable to strengthen and build up their leg muscles through flat work and their conditioning regime