It would be easy for them to make this an option that we can set though, in fact, another option should be that before update i am notified that there is an update, and only when i authorize updates for that app after i was notified does it DOWNLOAD them.. it ain't rocket science!
1) Library
2) On the library list, right-click game you don't want auto-updates for
3) On the right-click context menu, click Properties
4) On the Properties window, click the Updates tab
5) On the Updates tab, click the dropdown under Automatic Updates
6) Change to "Do Not Automatically Update This Game"
Granted, it's a pain to have to do that for every single game (somebody made a tool once to do it for all games but that appears to be out-of-date), but I did want to point out that the option is there. Also, relatively few games have frequent or large updates (TF2 and most source-engine stuff, Dungeon Defender, etc) and the others tend to be pretty infrequent about it.
But steam feels like an intern coded it and thats even now, many many years after the nightmare that was the first steam beta with css
I understand your frustration with it, and there are some glaring omissions (the game categorization feature is kinda sad, the aforementioned inability to set the update option globally, etc), and there are some longstanding technical problems that plague a certain percent of the users (servers available to take your money but too busy to send you your game, install.vdf tomfoolery, etc) but it's waaaay above intern-level. I've seen software written by interns. I've had to understand it, maintain it, and design and implement the replacement
This is a different beast.
Anyway, my point isn't that steam is a great piece of software. It... isn't. I like the service, I'm very grateful to the company from a couple of different angles, but I only have a truce with the actual client software. But if we lapse into the disproportionate reaction of condemning its every 1 and 0 to various layers of the underworld we subvert our own rationality. That can be fairly entertaining, of course.