It was important to myself and my parents that FI ask; they're very traditional, and I'm very close to them. It wasn't really about permission, it was more consideration that they should know what's going on. Also my dad needed to give the "You're family now too, but if you hurt her I'll kill you" (as did all my male cousins when we announced our engagement...thanks Italian stereotypes for being true...).
I'm really glad he did because he told me about it afterwards and my parents, especially my mom who I've had a difficult relationship with, said some really beautiful and loving things to FI about me and it was really lovely to hear.
We'd been together 5 years when FI proposed and to Jen's point, though there was never a doubt, if they had said No, we would've gotten married anyway, though would've obviously had a discussion about why they felt they couldn't give their "blessing."