I confess to being baffled by the indignance here. If a customer wants to guarantee a seat in F, this is the way to do it. What on earth is wrong with UA nudging people in that direction? I have friends with mileage balances in the hundreds of thousands who'd never notice 20K miles gone from their account. They're also generally too busy to make a point of upgrading every flight, so they just play the CPU lottery.

But if they happen to want to sit in F for some reason, why shouldn't they be reminded they can guarantee their seat by burning through a few miles? To me it's a win-win, and not remotely insulting. A CPU is indeed a perk -- but not a guaranteed perk.