I like the idea conceptually, but the different ideas about dates expressed above, does portray some of the challenges with choosing dates for "builds." It can be a very subjective thing, so if we are going to do it, we'd need to decide exactly how to do so. I don't know what is commonly done for build date with these other projects that deal with betas and prototypes.
I do like the idea conceptually of adding valuable data that is helpful in identifying different discs. For example, I strongly prefer the way we handle datnames for PS2, versus PS1. PS1 is standardized "Demo 1" "Demo 2" "Demo 3" and the numbers can change back and forth depending on dates and such. So what is Demo 1 now may change to Demo 2 later, etc.
This is all a compromise of keeping things under control, while adding enough detail to distinguish releases. The challenge is, different people use dats differently and have different preferences about what information they want to see in filenames.