I'll chime in here, as someone who can understand both sides of the argument (For: Easier Patching, Social, Multiplayer - Against: Another app eating system resources, steam's quirks, privacy, lack of reliable internet connection) and as someone who's worked in IT Infrastructure, it seems to me that some folks are missing the point.
I know that Steam can be a PITA to deal with (heck, I'm not crazy about it at times), but it provides a lot of the infrastructure that the devs need and they don't have to double up their workload for updates + maintaining servers, network infrastructure, database backends, etc. And seeing as they're only about 6(?) guys, that's a lot of work to do. Heck, it takes a team of 6 just maintain the servers in the small building I work in (and that's just only 500 people).
To be able to create a standalone version, you'd need to develop an API and back-end to allow the launcher to talk to the server to authenticate your game, check for updates, process transactions, verify that they aren't fraudulent, etc. Well... that requires more time and work from the devs, possibly hiring a specialist (or two) to help develop the system, then they need to learn how to maintain said system, fix it if things bork up, etc., etc. Thus, taking time away from creating more content and ironing kinks out. Also, you lose out on multi-player and possible DLC (as that takes even more work to add into a system).
By using Steam, the devs can just use a common API and tools to handle the bulk of the above work and technical issues and all they have to do is focusing on putting a quality product. Steam takes a cut of the profits, but it would end up saving the guys a lot more time and money in the long run as someone else is dealing with the infrastructure and supply chain so to speak... let's face it, renting racks in a datacentre (or hosting your own) ain't cheap and I should know, I rent a rack of machines from a datacentre in Montreal and it costs me a pretty penny and I have to maintain it all on my own (apart from hardware replacement and cabling which is handled by the datacentre) and they make sure I pay for everything... electricity, connectivity, the space the rack occupies, access to a remote KVM...