A genuine question. Do most other airlines have substantial 'Club Kitchen equivalent' for J? I don't do much eating between meals so I am not too familiar with it, although I am aware of some Asian carriers having pot noodles etc (!).
If other carriers aren't doing a substantial in-between food it probably doesn't motivate BA to do it.
Anyway, maybe BA could have some longer-life options like cereal bars as mentioned by some people above, because I heard that Club Kitchen 'fridge' space is an issue?
Another thing. If I have a tendency to get hungry between meals and I am aware of the lack of food, I think I'd bring some food along with me, even though I'd probably grudgingly do so unless I'm in Y/Y+.