I generally don't mind buying Steam games, but when I can get them directly from the developer without the hassles of Steam, I almost always do. I know the developer benefits financially while at the same time I don't have to start Steam and deal with its constant updates and advertisements every time I want to fly.
Unfortunately, many people almost exclusively buy and play games through Steam or its various competitors. Steam is getting paid for access to their very large user base and its captive advertising channel. But are there a significant (profitable) number of Steam users that will play Aces High for any length of time? It is a gamble.