I also think you need look no further than the new user interface. There are texts that overlap, texts that go offscreen even though most windows refuse to (except auction), sometimes even more than just the shortest of info requires scrolling, scrolling bars are often of poor width, some title texts are huge and thus waste space needlessly, etc.. Colours are a matter of taste but I think they are horribly pastel: it's all under relatively simple dev control to not be so poor and nothing to do with the engine itself, yet we have gone through several patches without this and much more actual functionality having been restored.
The good core programming is mostly two decades old and is still what makes this game special: the loot engine and dynamics economically. Agreed, lots of people dislike the waves, but we live with them.
There has even been great stuff such as mothership damage inside ships with explosions and all under cryengine, but they were quickly cancelled again. The most I hope for in UE5 is a decent look and feel and certainly nothing great, but then again, I'm so old school I can remember when gaming graphics were little more than wire meshes and yet playability could be really great if well implemented. Give me playability and I'll be happier than with awesome reflections and textures any day.