"The solution to bad metasystems is not to ban metasystems, it is to design better metasystems that allow these things in a more disciplined and more flexible way."
Yea, I think KVO could be done better. As I recall, Ember properties were pretty neat, and had a nice way of specifying dependencies. A lot less awkward than a bunch of + (NSSet )keyPathsForValuesAffectingValueForKey:(NSString )key methods.
I'd also want more strongly typed keys, less strings everywhere. I do use NSStringFromSelector as much as I can, but strings are unavoidable in IB.
Also the handling of one-to-many dependencies could be made a lot more intuitive as well.
