I have to confess I don't see much of the logic in this. If there was cost-cutting to do, I wouldn't see a problem in cutting back alcoholic drinks in the rear cabin, but reducing all catering to birdseed is downright insulting and nonsense.
As for stocking up in the lounges, the food choice at the Terraces lounge in GVA is (outside breakfast time), guess what? Birdseed
(or the local Swiss equivalent).
As others have pointed out, taking healthy alternatives is nigh on impossible these days. You can't take fruit with you.
I also don't look forward to the odd smells you get when everyone brings on there own à la American domestic.
No doubt the beancounters at BA have taken into account the increased cleaning bill for clearing all this junk food up once passengers disembark.