Game aren't tied to the size of a single DVD though. As well as multi disk games there are games with download content, and Forza even has content across 2 disks that can be accessed from one.
The only other thing that could be done is ditching play-from-DVD, and stiffing Core / Pro (20GB = 10 GB) / Arcade / 4GB users. If MS have any sense, that's about as likely as upgrading the GPU or releasing a Bluray model with Bluray games.
Games are tied to the size of a single DVD. Your game can be partitioned across several of these but at any given time your game is content is limited to 7GB. In a linear game like Gears of War or Uncharted this isn't a big deal, but there's a hard limit to how big an open world game can be.
While DLC helps, it's not mandatory. If you're going to have mandatory installs for DLC then why not have mandatory installs for disc games? Sure some people are going to be size constrained depending on what hard drive they have or if they have one at all. That was a mistake on Microsoft's part. Even there they could do better by their customers. There are cheap 250GB upgrade kits for PS3.
But you're talking about MS "fixing" something in a way that's against their (and a lot of 360 owners') interests. That's my only point - if you want more capacity that's understandable.
Though it may work for Microsoft doesn't mean that it isn't broken. And yeah, I do expect companies to remedy things that aren't in their own interests. Microsoft makes decisions that aren't in the interests of gamers like the lack of a mandatory hard drive, or the paltry 4GB in the slim arcade units. If Microsoft acts in ways that are indifferent to the interests of its customers, why is it so unreasonable for its customers to act in a way that's indifferent to the interests of Microsoft?
An example pertinent to the topic is the size restriction for DLC and XBL arcade games. These are pretty much industry wide decisions. They affect PSN through Microsoft's licensing tactics. Capcom had to haggle with Microsoft about the size of SSFT HD remix, and this would have impacted the PSN version. Should Microsoft fix these things? Yes. They won't, but they should.
I think the reason we go back and forth on this is because what you consider bizarre nitpicking on my part, to me, is perfectly natural and healthy criticism. In particular, I do more of my gaming on the PS3 these days. I have a 360 and a live gold account, and I truly wish I could get rid of both. Increasingly I find the PS3 is the right fit for me, so while you may see this as much ado about nothing, I think it's another raw deal served courtesy of Microsoft.
EDIT: Just read in the Crysis on consoles thread that MS increased the XBL arcade game size limit to 2GB. Kudos to them.