You're missing a much larger picture but whatever
Actually I'm
avoiding the much larger picture. I had no qualms with buying a HL2 steam package, but that's not to say that I fully endorse the steam method of distribution for other developers and/or publishers. For most games, especially single player games, I'd rather have a hard copy sitting on the shelf; too much can happen in a few years' time to disregard the possibilities of not easily reobtaining a copy of the product.
I made an exception here because Valve is already very rich, they are going to be even more rich around a month from now, and they're overall a large team of very talented individuals that will be around for a long time to come. Taking that into account, I would've still bought retail had the prices and content been the same. Silver is just a much, much better deal than the retail product, though, so it wasn't that difficult a decision.
Again, I get more content for my dollar, Valve gets all of my money for producing said wondrous content, and I'm not too worried about the big V dissolving a few years from now. That, I think, makes the both of us happy.