[cll]

"significant minority of people opposed to any links with the United States, they will be a
constant and intense irritant to the political process."

Well, you in the mainland have close to half of your population consisting of characters like democrats, the ANSWER crowd, greenies and similar assortment of lefties, which are a constant and intense irritant to the political process already.

[rrrod]

I have travelled in and out of PR for biz. Let the folks in PR make their own choice. But the status quo needs to be changed. Great place to visit BTW

[quadrant]

Half is a bit of an exaggeration; a third would be a more likely percentage.
However loony these people are, most, with the exception of the Aztlan nuts, accept the legitimacy of the United States and want to be a part of it.
There is a minority in Puerto Rico that doesn't want to be a part of the US and will never be reconciled to it. People of that persuasion will become violent, sooner or later.
It is foolish to inflict that sort of stress onto your political system.