While in theory it sounds like a great idea, the backend for it would be horrible as well as the overall experience. The reason it is bundled is for simplicities sake along with some technical reasons (I assume). An example we will use is the Direwolf20, Mindcrack, Ultimate, Tech, and Retro packs. So the user can choose from 5 separate packs to download, and 5 downloads that FTB has to host. Inside each pack (which is zipped) includes the file structure needed to launch minecraft, all the mods, the configs, etc. Now if we take individual mods separate of each other we have somewhere at 200ish individual files (This includes mods and configs, since minecraft is downloaded from Mojang themselves) that would have to be hosted by FTB. Then instead of unzipping your the pack in a set location, the launcher would have to create each folder itself and then know where each mod itself goes (Whether it is a Jar mod, Core mod, Mods folder mod).
