Don't know if I'd call myself an old fart but I do know the value of a dollar now that it's worth about 39 cents. To me, one that's had to work for everything I've ever gotten, it's hard to justify "upgrading" when I've seen the latest and greatest glitch and fail on more than one occassion. Let's look at some of the operating conditions a radio system has to deal with:
1) If used around water, 2.4 is subject to reflection and distortion, not good for boats, floatplanes or in rainy conditions . This environment would be better suited for 27MHz, 72MHz and 75MHz as they are not affected nearly as much
2) Due to reflection, 2.4 is not really usable for submarines as that frequency range won't penetrate water easily. For subs, your best option is the longest wavelength you can get, 27MHz
3) Using 2.4, while being almost impossible to shoot down, can cause problems when it comes to compatability. Using Futaba as an example, there is FASST and FHSS. While they are both 2.4, they are not the same and therefore, if you have a FASST transmitter, you can't use an FHSS receiver.
As a lifelong mechanic/electrician/avionic tech, I believe in using the right tool for the right job. To me, 2.4 isn't the right tool for many applications but, rather, it's a new gimic being fed to us by the manufacturers as the greatest thing since sliced bread