Remember, outside of the US LTE is essentially a non-feature, so there are lots of people who don't actually care. Then there are the people who could use LTE, but find their current network fast enough.
I live in a place with no LTE, but honestly if it were to degrade battery life I'd rather live without it: faster network is always nice, but the current one is fast enough.
The difference between Windows 7 supporting IPv6 and the Nexus 4 supporting LTE is that LTE requires a physical chip that costs extra to manufacture. Why force all users to pay extra for an LTE radio if most users will not see any benefit from it?