Seems like Google also realized there aren't much improvement on the Android front from 2013 to 2014. Galaxy S5 is almost the same as S4. Z3 is just a slightly smaller Z2.
What I hate about the Nexus line is the very limited storage. If there's only one variant which is 64GB of onboard memory then the past Nexus phones could have done better. I hope that the Nexus X will have a 64GB variant immediately.
Really, at this point, manufacturers could adopt a two-year or eighteen month update cycle instead of the annual one they maintain now. I use a Nexus 5 and, even though there's always nice stuff coming out or leaking, the only thing that makes me even think about upgrading is the Sony Xperia Z4, and that's six months away or more. By that point, the Nexus 5 will be well over a year old. And it still won't really be outdated, just not top-of-the-heap anymore. It's really wild to me how hardware progression has plateaued so hard lately, since it was so furious back during the early days of Android. Back then, when you bought a new phone, you were lucky if it stayed current for a week before some new superphone was released and everybody flocked to that.