As someone who first discovered AGS back when it was at 2.72, and who for many years refused to update to 3.0 due to preferring the interface in 2.72, I can tell you that I'm glad I finally bit the bullet and forced myself to use the newest version.
It's taken a short while, but I now prefer the newer versions over the older ones, plus I get access to all of the cool new features (and better compatibility).
The biggest hurdle for me was the slight reorganization of the interface, but that can easily be fixed by moving the menus around (which is one of those cool new features I was talking about).
In short, I think you would gain a lot by upgrading. You don't have to, but I'd highly recommend it.
It's taken a short while, but I now prefer the newer versions over the older ones, plus I get access to all of the cool new features (and better compatibility).
The biggest hurdle for me was the slight reorganization of the interface, but that can easily be fixed by moving the menus around (which is one of those cool new features I was talking about).
In short, I think you would gain a lot by upgrading. You don't have to, but I'd highly recommend it.