FTB's made the decision that their worlds should be compatible across different Minecraft versions, which means each new version they have to wait for every single mod to be updated before the pack as a whole can be updated. FTB also includes mods like redpower that have been historically slow to update, so a delay updating the pack to 1.5 is hardly a surprise.
If you're wanting to stay on the cutting edge FTB probably isn't for you - either look into smaller packs like the new tekkit or download mods into multimc yourself. Mods seem to have started automatically resolving block ids so adding them yourself isn't that much of a hassle.
If you're wanting to stay on the cutting edge FTB probably isn't for you - either look into smaller packs like the new tekkit or download mods into multimc yourself. Mods seem to have started automatically resolving block ids so adding them yourself isn't that much of a hassle.