5e was a huge opportunity to do some modernizing to the traditional ruleset of dungeons and dragons. They did a great job with this in certain aspects of the game, like the updated spellcasting rules. However, my biggest complaint by far about 5e is how they made almost no updates to the traditional attribute system d&D has always used, which frankly has a lot of problems.
Pillars of Eternity is a great example of how the 6-score system of D&D could have been easily updated into something more coherent, sensible, modern, and balanced. Not only do the 6 attributes in PoE make more conceptual/thematic sense, but they are also designed with the mantra of being useful independent of class. There's no such thing as a dump stat. Some stats may be more useful for some builds than other stats, but it comes much closer to being class-independent than D&D, which I vastly prefer because it makes character concepting and building much more engaging, with the potential for much more diversity, and opens up interesting role-play options.