"How" is very easy to answer - go into "Maintain menu access records" and click the button that says "Update all to newest programs".
 
"Why" is not so simple. We started out with all new ones but have ended up going back to some non-GUI screens because of various issues. If you can use the GUI ones it's very handy, as they are truly GUI - you can click anywhere without error and make entries/changes to the fields.
 
My suggestion is to log in as Admin (not simply someone with full Admin rights but the actual default "Admin" account), as that always has the latest new programs, and try it out. Once you've figured out which (if any) of the new ones are desired you can change just those ones for all users in the menu app. Can't remember the button name but it's pretty self explanatory. You just need to know the old and new names. Note that most (all?) of the T7 ones have an RWN extension rather than a RUN one.

Most of the core Inventory modules are pretty solid. The Sales modules are most of what we had to change back for some of our users.