Because the Ruling Class intends to use it to put out the Tea Party fire lit by We the People.
I really believe that's all there is to it.
The Ruling Class wants a more compliant electorate.
It's disgusting to contemplate. But likely true.
In the absence of immigration reform...the probability of the Ruling Class being deposed successfully rises dramatically.
“Immigration Reform” sufficiently dilutes the power of We the People that the Ruling Class might yet be able to post-pone the inevitable.
I don't see much compliance in 20-40 M illegal immigrants from south of the border. They may support the dems now, many, because it gets the foot in the door, but their loyalties do not extend to the dems, rather to themselves and their "race", as it were.