The most basic argument I can make in favor of SD cards and their continued use is that they're cheap. They may not be as cheap per-megabyte as a hard drive, but they're much cheaper in terms of actual things you can buy. You may not ever need more than 2 or 4 GB of storage for your Wii -- because there are no HD movies to buy, among other things -- but good luck finding a new, reliable 2 or 4 GB external hard drive. Most likely, you'd have to get a much larger hard drive, and pay a lot more for it. And that's assuming you'd even get to pick your own hard drive. Chances are, for Nintendo's granny-friendly console, they'd produce their own external hard drive, which would certainly cost a lot more than the cheapest no-name unit you could grab from Fry's. But you can use any SD card, and look -- here's 2GB for $1.50. For most of us, it seems likely that 2GB would be enough. It's enough for Dave, and he's cleverly made having every Virtual Console game part of his job. If it isn't enough for you, just drop another $1.50 and swap out on the extremely rare occasion when you run out of space.
But the storage medium itself may not be the biggest issue people have with Nintendo's solution: rather, the file management is. In order to play something stored on your SD card, you'll have to transfer it from your SD card -- unless it's a Guitar Hero World Tour song, because Vicarious Visions is apparently awesome. Right now, to save to SD, you have to go into the Wii menu, pull something off of the Wii's memory, and stick it on the SD. Nintendo's big innovation coming in the spring will make it so that you can buy stuff from the Shop and save it directly to the SD. You don't have to clear space in your Wii "fridge" when you buy something. If you do need more space, you can move stuff around to the SD card after you've bought a game. Basically, it allows you to do your file management at a much more convenient time, rather than after you've tried to buy something and been forced to back out.
And even the current SD implementation is easier than the way most of us have changed games since we were born. Remember getting up? Moving stuff around in a menu requires less movement than changing a cartridge or a disc. Basically, what I'm saying is that any method of swapping games in and out of your system that can be done while seated ten feet away from your system is great.
