I agree this backstab thing is an issue, but you know how i fixed it?? i didndt, i got the amulet with teleportation and every fight i equip it in battle on the person who moves first and teleport them into backstab position or high ground and then unequip the amulet, repeat for every character: profit.
And im getting really tired of doing this, i agree the warrior should only use his thaco to determine hit not have any bonuses for backstabbing.. I find myself spamming jump button more then anything else, and it doesnt even have a hot key, where is logic behind that??
I can tell you that that sort of repositioning is frequent in actual physical fights, especially those with complex terrain. So it makes sense to me just fine.
