This is kind of a ying/yang issue.
I understand why the camera manufacturers are not moving to DNG. However, we must also understand why Adobe does not want to continue to support older releases of their software. Pretty much, both points revolve around financial, rather than technical, issues.
I want Adobe to continue to enhance Lightroom. To do that, they need a business case to justify the development (and associated) costs. Part of that business case needs to include the upgrade pricing and market assessment of acceptance, which includes a price vs volume analysis. I am sure that a similar analysis resulted in the LR4 release having significantly lower initial and upgrade pricing.
I would like this enhanced function sooner, rather than later....and am willing to pay the (reasonable) cost of an upgrade. Others may decide to hold off if they have no need for the new function and do not have a new camera needing support. For those with new cameras, Adobe is nice enough to provide an alternate means, DNG, for support. Each person can make their individual choice of cost or effort to support their needs.