I have been irritated by this problem as well. So far this year I have had to follow up on four out of twelve stays (33%). I find the problem occurs even when they ask my preference and even when they fill out the card. Sometimes, they never ask.
I write an e-mail to Starwood Customer Service for each occasion separately. And I insist on additional Goodwill Points for my trouble. Customer Service never offers them, but when they pass the e-mail along to the individual hotel, the hotels almost always oblige. I have received replies from some hotels, both e-mail and snail mail. My perspective, if Starwood drops the ball and I have to follow up, I should be compensated.