They've been planning to add an officially sanctioned TFC pack to the FTB launcher for some time now. And then Minecraft 1.5 happened and mods are taking forever to update because the way textures are handled changed completely.
Mind you, said pack will likely only be TFC itself, maybe with some convenience mods added, like NEI. You must keep in mind that TFC is not a content mod, it is a total conversion. It is not meant to receive the same content mods as vanilla Mincecraft. Trying to add such mods would be like trying to add a Half-Life 2 mod to Crysis, if you will. Both are shooters in which you fight against aliens, but they're completely different games.
I've played TFC myself and I can give you some examples on just how incompatible it is:
- Rei's Minimap bugs out and shows most landscapes in black and white (though aside from the colors everything works correctly) due to the way TFC does texture overlays.
- Inventory Tweaks bugs out and occasionally makes items disappear when trying to stack them, because of TFC's custom item properties like size, weight and temperature.
- The custom terrain generator cannot not spawn vanilla or mod ores. Not just "doesn't do it", but quite literally "cannot do it". There is no vanilla "stone" in which ores can spawn. None whatsoever. Zero. Nada.
- The custom terrain generator is incompatible with post-generation worldgen like Redpower's volcanoes and so on.
- Many vanilla sub-blocks, such as stairs and slabs, do not exist (they are handled by TFC's chisel).
- There are no strongholds and no The End.
- There are no NPC villages (screws over Thaumcraft and Mystcraft, among others).
- There is no Nether (the list of mods this screws over is too long to include here).
- 95% of all items that people recognize from vanilla, even if they look the same and have the same name, are not actually vanilla items. Even things like dirt, or oak saplings, or torches. As a result, adding any content mod whatsoever requires you to also install a support mod where you need to define by hand extra recipes that serve no other purpose than to transform TFC items into otherwise fully identical vanilla items.
Some guy went and did this for Thaumcraft. He needed over 120 conversion recipes just to make it possible to access all the aspects necessary to complete the currently available research tree (including making recipes for crafting the various vis shards, because as mentioned before, custom ores cannot spawn). And even then that's only one mod, and it still doesn't quite give you the same experience.