You know, that kind of sucks ... there are many machines around that are still on 32 bits.

I keep my own Ubuntu laptop (dual-boots to Windows) on 32-bit builds (both Linux and Windows), simply because I have less problems that way (mostly with hardware drivers, but also with software). I keep the Amazon EC2 instances I maintain on 32-bit images, simply because they are cheaper. My Android phone is also 32-bit and will be so for a long time. My other phone, an older iPhone 3GS, is also 32-bit. My servers, prior to Amazon EC2, built with ARM processors, were also 32-bit.

And when I was playing with MongoDB, do you know what I did when I discovered that the 32-bit build was basically unusable? I ditched it and never looked back.