Re: Shame they cut a corner on this premium product
Probably because there's a lot more involved than you think. Not only do you need the right modem chip (and last I checked, only Qualcomm's chips tick all the boxes), but you also need specific antenna design to cover the bases (physics gets in the way there). Also remember, US LTE bands and other LTE bands are mutually exclusive due to prior allocations. The biggest hangup is that 1.8GHz--LTE Band III, the most universal one--was already taken by the US government (the military, I think) long before LTE was ever a thing.
There's a StackExchange discussion about this.