Lots of reasons. High speed sand or snow bashing, for example. Also, when exploring off-road, there's many times when we're in high range and don't really need to go into low, but could use a locking diff (or two).
The Jeep Rubicon has the same problem. Those owners have figured out a few ways to bypass the low range only switch.
A personal reason is I've used locking differentials in my vehicles for 35 years and can decide when to use them. I'd rather not have an engineer (or attorney) dictate through vehicle design when I can use a locker. GM did a good thing when they put a switch to turn off the TCS and StabiliTrak in high range. I want that same choice for my E-Locker.
