Emerikol
Legend
What is fun and engaging varies between people is all I can say. The fear the undead invoked in my PCs cannot be easily duplicated without those rules.And yet I'm on the "the world can affect player mechanics" side. Emphatically so. Like I have said I am an advocate for changing subclasses - and if that isn't impacting player mechanics I don't know what is.
What I'm not an advocate for is crippling the player character. Change isn't the same as crippling. That which doesn't kill you makes you stranger.
And the problem with just about all these is that they are boring. The problem is that literally all the consequences you have named there fit into one of two categories:
It's not the fact that they have an impact that's the problem. It's that they are all crippling and strictly negative.
- Taking away someone's toys and crippling them until they get them back (removal of spells, level drain, ability score drain)
- Changing around numbers (magical ageing, ability score drain)
What I like are consequences. I recently gave someone a homebrew Hand of Vecna and the way it worked was through a corruption mechanic; whenever they used one of the major powers they marked off a Mark of Corruption. And each time they used a major power they had to fill in a circle - fill them all and they become an NPC. Just a Taste and Megalomania went fast. How fast he got corrupted was up to him.
Marks of CorruptionO Just a taste: The first time you reduce a foe to 0hp after a long rest they return as a zombie under your controlOOO A touch of death: At the first level you look as if you haven’t slept for a week. At the second you look gaunt and haggard, and at the third like a lichO Blight: Small plants die and larger ones wither in your presenceO Megalomania: Gain a tendency to speechify. You have everything under control. So you think.
Far far more interesting than "You just took level drain. You lose your best toys and take -1 to rolls". I'm on the "we want this removing things trash out of the way because it's clogging up where interesting things could be as well as making things less fun". And you know what this does? It makes the PCs far more likely to risk the consequences because they know they will be interesting. And their character will get stranger, not just crippled.
And while you may or may not be in this group so don't take it as I'm saying you are but there exists a group of what I would call entitled players who want inviolate protections from what they'd view as DM interference. Those people I save the trouble. I tell them they are eternally protected and send them out the door.
And I'm not saying your thing is bad. Everything doesn't have to be exactly what I listed. I think those things were good though.