xigbar
Explorer
I've always understood the "5 foot rule does not provoke A..'s" because anyone can take a step backward with no trouble, but to intentionally go further requires someone to turn their back on the opponent in order to move away.
If one could step backward 10', 15', etc, without needing to turn one's head to see where one is going, then all good. Figure out the mechanic to make this happen so someone won't trip over unseen tree roots, uneven tiles, etc and you're groovy.
Short of unusual terrain, there are no rules for tripping on loose roots. In which case, I don't see the problem. In unusual terrain everyone trips anyway.