No doubt the tow ratings have increased on the 1/2 ton trucks of all makes. The question is, are they building a better truck now or just adjusting their tow ratings to be more competitive and removing the built in safety margin previously incorporated. Personally, I think a little of both. Transmissions are much better today with 6 speed options which allow a better towing performance out of the same size and HP of engine.
I will state this however after recently going from an F150 5.4 4 speed to a 2500 HD 6.0 6 speed pulling the same trailer with the same WDH. The F150 had plenty of power to easily pull my toy hauler but the 3/4 ton has way more stability in windy situations. With the heavier springs and drive train the comfort difference is night and day. If one must use the 1/2 ton as a daily driver, then maybe it is a good option with the correct setup otherwise, heavy duty is better...hands down!