Ally is not massively pleasant to weld with, needs different welders. There are a lot of really cool steel alloys atm, and not very many ally ones. A lot of this will be to do with fashion, and you may find that it comes back into fashion in the near future, the bike trade is cyclical. Personally, I have the capacity to weld ally, but what with the lack of choice in tubing, drop outs etc, coupled with the pain that it is to repair etc.... have never been particularly drawn to it.
Also, if you're doing it properly, you need to heat treat the frame after welding on most decent alloys, which is another PITA and regardless of how it's made the frame will inherently have a limited fatigue life, unlike steel.
Ally is not massively pleasant to weld with, needs different welders. There are a lot of really cool steel alloys atm, and not very many ally ones. A lot of this will be to do with fashion, and you may find that it comes back into fashion in the near future, the bike trade is cyclical. Personally, I have the capacity to weld ally, but what with the lack of choice in tubing, drop outs etc, coupled with the pain that it is to repair etc.... have never been particularly drawn to it.