10' steps (or double 5' steps for that matter) are pretty broken, if you can do them at your leisure.
The concept of the 5' step has nothing to do with "mobility", it's just combat dynamics, so you do not just stand there trading blows, but shift positions all the time.
But with 10' steps it's trading full attacks versus single attacks (so following is pointless).
It totally twists what 5' steps are for.
Bye
Thanee