I'm still skeptical about what, exactly, people will be locking in with "unlimited" data. My suspicion is unlimited LTE - meaning LTE speeds - is a pipe dream.
It also occurs to me, since VZW has said they wouldn't go to tiers until as late as Q4, that there could be a promise to Moto that they won't make the switch until after launch of the Bionic. Remember, this phone was supposed to be out in late Q2 and to the extent problems are LTE related (which they probably are, at least indirectly, with the processor and we've seen the issues with the TBolt) I don't think VZW can cause Moto to lose sales by pushing a bunch of people to a different phone to lock-in unlimited. And let's not forget the Atrix - did AT&T throw a boatload of money at Moto or did VZW really want LTE, because all else equal you better believe Moto wanted that phone on VZW.
There's also the Xoom - was that rushed because of Moto (seems likely) or VZW as there is still no LTE with it?
I can think of other reasons, as well, but I'm willing to bet unlimited LTE is going nowhere until after launch of the Bionic. Don't forget, in many respects Moto is also a partner, and the bottom line is a dual-core LTE phone is going to be the VZW flagship and is going to really put LTE on the map.