I really wonder if the Mexican thing is cheaper than say Pizza (let alone burgers, or if you want to be hipster about it - Sliders) to produce etc.
I still say that ANY theme - pizza, mex, burgers, thai whatever would get old pretty quick specially for regular visitors... I don't quite understand why they couldn't change them around a bit on a seasonal basis.
Yes, I know, the mexican dishes change in BNE but it's still the same basic kind of thing.
As for the other comments - some people love Mexican or pizza or burgers and others can't stand one or the other... isn't this the age old problem of catering for groups? You can never please everyone can you? And yes I know the lounges have the "usual" options in addition to the "specials"(eg: mexican) but still... I can see the dilemma.
Either way our lounge offerings are still head and shoulders better than those in the US/Canada and most of europe. We tend to forget that sometimes. Just like QF J meals on short sectors... try a SFO-LAX on AA and then complain about the toastie or soup option on QF