during the beta, we had that mechanic for a while (battle consumes all remaining movement points) but there were lots of complaints about that system, so eventually the devs restored the old system of multiple attacks per season. i think two of the main arguments were being unable to loot a lair after you defeated the guardians (thus you could sometimes lose the liar when an AI army happened to be close enough and could just steal your loot), and slowed down wars against AI that would block their area with small stacks (which can result in a situation where you can easily kill them, but can't really progress since the AI just spams more units that slow you down)

don't know. i didn't really mind the limited attack during beta, but i also don't mint the new (and old) system we have now. i guess they restored the old system because many beta testers told them the other system was a bad idea/not fun.

I can live with it either way, but multiple combats per turn means a faster paced game, which is a good thing in my book. It also improves the viability of your best heroes, because they should be gaining a lot of experience in your stack of doom.

It does however somewhat hamper the AI, which is not very good at building a stack of doom. It has also been reported (don't know if this is correct or not) that it will only do one thing with a stack each turn, which would presumably mean that it will do one combat and then stop. If that's correct then clearly the AI is going to be at a disadvantage until it actually starts using multiple combats in a turn where appropriate.