I think it's a question of if expats in HK want to develop a deeper cultural understanding (and hence needing to learn Cantonese in order to do that). Not everyone does and with English as an official language anyway, people can easily live here without needing to learn Canto. That's their choice and I don't think they should be criticised for it. Different strokes for different folks and all that.
I lived in Paris before I moved to HK. I speak French fluently and was the only non-French person working in my division of a French company. I went to university to France many years ago and have worked for various French companies over the years so I have a reasonable understanding (and liking for) French culture. However, some of my expat friends in Paris had no real interest in integrating. They were happy with their expat lives with their circle of expat friends who spoke English. I felt that they were missing out on a lot of fun....they didn't understand why Parisians did things the way they did and they weren't party to some of the (very amusing) French jokes. But my expat friends were happy! And who was I to criticise their way of living? They weren't harming anyone. So I ended up with two circles of friends, my French friends and my expat friends. I did try bringing them together at my leaving drinks but it was a bit of a disaster. Definitely oil and water! So now when I visit Paris, I see my two circles separately. With my expat friends we go to the pub and drink and with my French friends we have 4 hour lunches at their apartments and put the world to rights. I love both!
Now I live in HK, I'm suddenly in that expat clique and I understand where Watercooler/others are coming from in terms of missing out on a deeper cultural awareness because I don't speak Canto (just like my expat friends were who didn't speak French). But you know what...I'm quite happy. It's not a language or cultural awareness competition. I have local friends (I work with nearly all locals), I'm told my Canto swearing is impressive and I can get by for the day to day stuff. At this stage in my life, that's good enough for me. I wish some of the posters on Geo would stop making it into a competition and putting expats down. It is GeoEXPAT after all. If you don't like expats, go find another forum.