"It's XXXXXX and XXXXX. My credit card's on that account, don't use it to download a bunch of games like you did last time, okay bro?"
Steam doesn't persistently store your credit card information. I'd be weary of any digital delivery service that did.
"Can you imagine how difficult it will be to bring a game to your friends' house to play?"
Okay, okay, let's just say your pal doesn't want to waste the bandwidth or time on downloading; that's fine. So, I don't know - as difficult as opening Steam up, navigating to "Backup games", burning it to a disc and walking it over? Personally, I can't imagine a mortal among us to tackle this Herculean errand.
"Wait a minute, I don't have any room on my hard drive left."
Gone are the days of juggling CDs and game installations to ensure you have 100MB of space left in order to pay tribute to the Windows 95 swap deity. If you're using an even remotely modern HDD of an even half-acceptable size (heck, even grandma's new HP for checking chain e-mails and visiting smileycentral comes with a 300GB drive these days), yeah, if you don't have enough space to install something from Steam? Not only are your computing practices more than likely idiotic to begin with, but you can most certainly deal with uninstalling some junk. Or hell, you've just proven you need it - so go buy a second HDD.
But you know what? The fact is, Gabe Newell, Valve co-founder, has gone on record mocking conventional DRM and stated, paraphrasing, that the mission of Steam is to make buying games, storing games, and accessing games easier and more convenient for the customer. Their content servers are widespread, well-maintained, and frankly - your aside about the "Butt Zappers server being slammed" is moot. Even the dreaded Slashdot phenomenon is a drop in the pond to Steam's full throughput. The recent roll out of of Left 4 Dead and Team Fortress 2 content packs have proven testament to this.
The only real complaint of yours that stands is with respect to re-selling your games - but really, tough shit. It's probably the only real remaining trade-off of digital delivery, so just consider that you're trading resale value for a few dollars in publishing costs the next time you buy a Steam game a bit cheaper than the brick and mortar box cost.
As a final note to answer any forthcoming "but, but, but, what-if!?" conjecturing, Valve has stated repeatedly that in the event they close up shop, a means for us customers to retain our purchases will be provided. If you have to crusade against digital delivery, don't go after Steam.
Life is a whim of several billion cells to be you for a while.