Sorry for long reply. So here is my point of view:
1) Every one has free choice, to use it or not. It's up to you to decide, not to me. I gave you only an option and if you want old rules, it's fine.
2) Kalah thinks it's a good mod. Duzeom too. Me - of course. So even if only we will use the mod, it was worth to make it.
3) About balance:
a) When you play on lower difficulties (1-3), the best way to win is to buy as much as you can of potions, develop combat hero and rush to the enemy. So don't tell me there are more important things to do if you want win the fastest way.
b) When you play on higher difficulties (4-5) it's hard to rush to enemy or develop combat hero fast. You are forced to build an army and create magic or tactic hero. Well, I prefer stealth hero first, and then create another one.But still, there are situations when using pois is really beneficial. You can cover your own units against ranged units. You can lose for example, 20 medusas from one shot, or one hero with poi. Wich is more expensive? 20 medusas, or potion of immortality?
c) When you play a campaign, hero becomes a war machine, that is true. Sometimes with pois you can win extremly fast. But sometimes your hero is so powerful that you don't need even pois. Depends on campaign I guess. But if you can win with one hero without pois, then creatures and other factors are not important at all.
Personally, I like to play without pois, because it's harder. If you can win easly without them, then you don't need this mod. But sometimes I need pois and there is always a temptation to spam with them to win some battles without losing creatures.