Would KDE actually require so much for all the features it gives or can that actually come down?
How much RAM is utilized depends on the components you loaded. "Convenience distros" tend to start more services by default. The KDE Workspace is very modular. You can disable/remove many things, esp. if you compile yourself. That said, it's not a workspace primarily for low-end computers. If it requires more RAM than your PC has, maybe look at LXQt.
It might not be that big of a problem this time around, when(ever) we move from v4 to v5, because hardware isn't evolving as fast as it used to. But KDE will remain a behemoth.
sudo apt-get install kubuntu-low-fat-settings
Basically, it turns off composting and file tagging services. It reduced the memory requirements and the CPU % dropped to something close to GNOME 2.x or XFCE.