We have already been making lots of changes to corruption.
The initial version of the mechanic that is out now turned out to be close, but not exactly what we wanted from the mechanic.
Changes are coming in a future release.
You will not be able to disable it entirely, but some of the changes should help with some of your frustrations.
1: Corruption will spread at a rate relative to the difficulty of the level. So in the Grasslands it will spread very slowly and take a lot of time to build up.
2: Some attacks will be able to 'burn away' and/or repel corruption. Chests and (lit) bonfires will also repel corruption.
3: Some enemies will have effects that spread more corruption, or interact with it in different ways.
Also, the corruption mechanic will play a larger part in the overall story of the game.
Also, also, the idea that the Corruption on the ground is so dangerous that you should never touch it might be a bit overkill. Corruption damage starts out very very small and then builds up the longer you are touching it - but it will take awhile to become super perilous. And, it will reset back to 'small' damage the moment you step out of it.
The idea behind the mechanic is to present more choices to the player - do I risk taking a few hits of damage to stand in corruption if it means I can kill more enemies or do I move to get away to somewhere clear all the time? Do I run through a small patch of corruption take a few hits to go collect XP or a Chest? what about a large patch? Do I go find potions enough to heal up and then come back here to collect those things?
While we would agree that in the version you are playing now, the mechanic is a bit rough, we have been working to make it better.