Lawmakers from all fifty states are being bombarded with requests for tickets to Obama's inauguration. When the norm is several hundred tickets each, some report several thousand requests. Questions arise as to how to divvy them up. Lottery systems seems most likely. A market does not.
Legislation looms to make scalping these tickets illegal. It seems like we should ensure that everyone should have an equal chance to get them, that we should combat those who would order a dozen, only to sell them for personal profit. But an a world of different preferences, a forced lottery system is more unjust than scalping tickets. The person who's mildly interested has the same chance as the die-hard fan. Without a market, there's no way to correct the randomization if the former wins. (Frankly, I'm surprised they aren't going by first come, first serve basis. That would solve a lot of problems. But part of the issue is the offices don't know how many tickets they are getting.)
Auctioning the tickets is not perfect, either. The curious but wealthy are preferred over the enthusiastic but poor. Without a prohibitively costly interview system, it's not possible to make it perfect. But denying trade makes it strictly worse.