I still don't like herbs

[SinsI]

Solution should be a way to get herbs consistently via normal gameplay, not nerfs or other changes to herb effects. My idea was to create some kind of flower pot item that sits in inventory and constantly generates new ones, similar to the way SI propagates itself. This way player will no longer be tied to the same level for thousands of turns.

[Blasphemous]

Herbs are actually magical in nature, that's why they don't rot.
There will always be something in the game that can be abused by grinders/scummers.
You change herbs, people find something else.
In a game as complex as ADoM, there is just no way to remove all methods of scumming.
Just leave it be, if that's how people like to play this game then so be it, let them play it their way, it's the price you pay for having MANY options in virtually every situation.
ADoM has always been about having enough things to play comfortably.
If you don't have enough means to remove corruption, either you play a fast game or find/make more corruption removing items.
If your stats are low because of drains or race/class you selected, you will inevitably try to raise them.
If not through herbs then through ID tension rooms and painstakingly gathering items and eating corpses.
If you don't like tension rooms, use chaos alchemy with Moonsickle and a great number of useless potions.

All you achieve by implementing the OP suggestions and similar ideas is a decreased flexibility.
There will ALWAYS be some grindy elements in the game; as soon as you remove one, another one pops up in your head.
If you continue on this path, this will lead to an extremely linear game, which is always a bad thing.
Let the diversity be, let it flourish and let players have a thousand options to choose from.
Let them make bad decisions because of not knowing what is the best course of action, instead of only leaving them with one.

As I mentioned somewhere else already and others pointed out - nobody is forcing you to farm herbs.
I have played both extreme herb farmers and characters without herbalism.
They are both playable and both fun, just in a different way and I wouldn't want that changed.