eric256 summed up my intentions for this idea rather well. This isn't intended to record what changed, or how often a node has changed, and it's certainly not intended to discourage abusers. Just a flag to say that it did change.
Anything further than the flag could still rely on requests to janitors or referencing the node history you've indicated, just like it happens already.
For the record, Corion's site sounds very useful. But tell me how I'd find that? This is the first I've heard of it, and it isn't like I joined the site yesterday. Even looking at Corion's homenode I see nothing about the node history available.