Obviously other carriers should also lock the boot loader then.
You might be right...
As a custom ROM user for many years... cracking boot loaders has never been the issue... just makes it a little faster/easier when unlocked.
OTOH... coming from Verizon's position, they are selling you Phone "A" with OS "1." If you are buying a phone and expecting constant updates... then you are living in denial and Verizon shouldn't have to put their support system at risk by floods of calls from idiots that flash (or fail to flash) their high end smart phones (I like to call them MPC's for Mobile PC's) and get stuff screwed up. That is not what the provider/Verizon is selling. They do provide OS upgrades but only after they are very satisfied it will not be a problem on the network... and they are usually successful with this as well. (Except with my phone when it came out)
I think it is cool enough that they are meeting demand by selling the cool high end phones we want (Sporting a Sammy Galaxy Nexus ((that came unlocked)) and a custom Jelly Bean Rom at the moment) phones that they know many of them will be customized... but expecting them to promote or support modding would be totally insane for ANY telco unless maybe Sonic.net decides to become a wireless/cell phone provider
If you start promoting or condoning modding then you are going to end up being somewhat responsible when the dweebs get it wrong and that is exposing yourself to service liability that no company could risk.
Sell them the phone, let them do their thing, it's all good. -- Mom was right.... I NEED fiber!