On top of that, over the years, the kickstand broke, the screen got scratched badly, my belt clip broke in multiple places, the SIM slot became really finicky, and even the plastic around the keyboard was starting to come out.
And a lot of the problem was performance: a 600 MHz OMAP3 was great in 2009, but by 2014 it was just too slow to handle modern websites, and the browser based on Firefox 3.5 (maybe 3.6?) couldn't even handle some newer websites. And to be honest, the RAM was low even for its time... only 256 MB, operated as a unionfs with the rootfs, plus some of the (very, very slow) eMMC was formatted as swap. Over time, most apps stopped working: I remember using Facebrick to access Facebook for a while, and it was nice, but eventually the author stopped updating it, and Facebook changed their API, so no more Facebrick. It got to the point where I'd only use the browser, terminal, camera, and dialer, because that's all that was useful.
About a year after getting my Nexus 5, I booted up my N900 to get some photos off it, and I found I had difficulty emailing them to myself because Gmail had changed their API and flagged my N900's connection attempts because they used the old API that was deprecated for security reasons. None of the emails went through, and when I got back to my desktop, Google took me to a page telling me it thought my account had been compromised.