Well this has been an entertaining thread! I decided to switch to the Lenovo w530 in order to get 32GB of ram, I do software development with a particularly hungry piece of server software. I need to deal with multiple VMs and quite often have 3 running - 32GB has been brilliant for that.
The downside has been moving to Lenovo/Windows

and man has it been painful. The Lenovo is a perfectly good workhorse machine but still suffers from occasional blue screens, driver issues etc. Stupid Intel driver problems automatically changing screen contrast, all sorts of little niggles.
I sorely miss the pleasure in owning a Macbook Pro, I've been to the shop and played with a rMBP a few times and am sorely tempted to move back. I can get around the 16GB limit in some ways by having some of my VMs hosted elsewhere and remoting onto them, not ideal but possibly worth the tradeoff.
My usual strategy of buying the machines, owning them for 18months then selling with 18 months AppleCare also means that when the 32GB models come along it wouldn't be too long before I got one.
6 months ago I switched from iPhone -> Android, MBP -> Lenovo and got rid of the iPad. Pretty much regretted each of those decisions.
Rambling post but essentially there are plenty of power users out there that could easily need 32GB (not always possible to have a server either especially if you travel a lot) but then the overall Mac owning experience means I'll put up with 16GB for a while yet.