for some of you who use DirectAccess probably familiar with the following link
Recommended hotfixes and updates for Windows Server 2012 DirectAccess

as far as I know and according to TechNet, DirectAccess hasn't change a bit from 2012 to 2012 R2 servers.

I use DirectAccess on Windows Server 2012 R2 and I'm surprised to see that there is no single update from that list the applicable with either Server 2012 R2.

if it's true - shouldn't there be a documentation that talks about the differences of the DirectAccess Client\Server from 2012\8 to 2012 R2 \ 8.1?

I'm asking because I want to make sure those updates are already include or not needed for 2012 R2\8.1 and not "forgotten" or something.

I'd say that they are so "old" that they are included in 8.1/R2.

I don't have a either available but if you have you can validate the version numbers of the files in each update against a 8.1/R2 machine. Updates are checked in before a cutoff date (when the buildphase of the next version ends) are included in the next release unless they are deemed to be faulty or the functionality has been decommissioned.