USB Loader is a great piece of software, as long as you get the install right, find a compatable HDD enclosure and then ensure that all your games run under the correct IOS natively as even patching the non compatable ones fail to run. i.e. Mortal Kombat etc ..
But I agree its a pain in the arse having your PC close to the Wii and you can only go so far with USB cable length.
I think the perfect Mod would be a combination of FlatMii for Disk Loading and Streaming, but also acting as a hardware USB Loader for any plugged in HDD. I'm sure that the team could burn an ISOLoader equivalent onto a Chip somehow.
Next Generation perhaps?
something like that is being developed from the looks of it. check:
Matrix WiiZii mod hooks to external SATA HDD for speedy ISO loads