Just since becoming a Diamond, I've stayed here ~5x or more now. I've only received a true upgrade 1x. Otherwise it's always "city king" to "exec city king" or "bay view king" to "exec bay view" which of course is meaningless for Diamonds.

It's really up to you to decide whether to raise a fuss. Personally, I don't. I frequently see foreign guests at EL trying to negotiate something with the staff upon check-in and clogging things up. I just think that's bad form. It's been said over and over in this thread that there's no harm in just asking. I can't disagree with that. But if you get a no, I wouldn't push it by pulling out your App with available room inventory and such. I never even ask for upgrade in the first place in Jpn, largely because I'm Jpnese and feel uncomfortable requesting things like that in Jpn. After a streak of many non-upgrades there, I admit I started to get frustrated. But they did finally upgrade us to a suite for the first time this past winter, and now I can rest easy knowing that I can be upgraded without asking if it's meant to be.