I think it's a bit of App Store limitations Massie. It seems to be designed to only offer one version, similar to how repos work. Updated apps replace older versions. I'd imagine the weather channel could release a legacy version, but I'm not sure it would benefit them much.
The iOS 6 requirement stems from programming. If they utilize anything not supported by earlier iOS versions, the app won't work with the older versions. Since these additions make programming easier, they get used more and more. The impact to users is generally negligible. Anyone with the 3GS or newer can get ios6. Outside of jailbreakers and people on phones that predate ARC, there's not any impact. That really eliminates incentive for TWC to put in the work to keep support for older versions of iOS.
Trackr, were you not using cydia much the past several months? Most users choose "make my life easy" which saves shsh blobs on cydias servers each time you're in cydia with a new iOS signing period. On the 4, it's possible to use those retrieve those blobs from the server and upgrade to 6.x firmwares.