Their hearts may be in the right place, but I
don't like the idea.
I like demographics and statistical breakdowns as much as the next nerd, but even if it is optional, there's an expectation to answer (and to do so honestly). It has no bearing on anything, and what's to stop a homophobic admissions counselor from discriminating?
More than that, just as students of Asian descent have seen pressure to limit their numbers, who's to say the same couldn't happen for non-heterosexual students.
And quite frankly, it's none of the government's business. There are no benefits to this, but there are potential pitfalls.