Maybe you need to use your phone's battery for making phone calls instead of acting as an AP. Maybe you want your email/IM's to be ready to be read when you pick up your device instead of having to wait for it to connect & sync. Maybe you have to leave your tablet in place & connected doing...
I've been eagerly awaiting the release of the Surface 3 LTE (In fact I came across this thread googling around to see if a releases date was announced yet.) & I'll tell you why LTE is a must for me.
While tethering is great for occasional use it has it's down sides to. Your really hammering...
