In some respects I wish they did more of that on an exception basis. I was ~$50 short of platinum two years ago and $7 (!) short of the next milestone last year and annoyed because both times I had YYZ-YXU flights that year that were cancelled where WJ paid for ground transportation but didn't credit me anything for the 'leg'. I talked to agents both times but no dice. I an not sure of the value proposition of platinum to gold for me but feel the united one is a different beast given their wide body service and presumably increased odds of international business upgrades. I still wouldn't pay it tho!