Man i just couldn't do it,this topic needs way too many exmples and decritions to achieve the proper answers.
So i'll just say YES i agree,the BEST way to acvhieve all of it ,is not by reinventing any wheel just by adding DEPTH to the game play.
here is a perfect example RENKAI system as to depth other games do NOT achieve including Wow.MOST games have generic hotbar spamming,1-3 second delays.it seriously does not take much thinking when you are just spamming buttons on the hot bar.
The Renkai onlyu scratched the surface ,so much more could have been expnaded on and improved.The other basics you need for depth are utilizing,aging,terrain,elemental properties [fire/earth/wind],weather,moon phases,day/night,various melee and magical resistances and properties.I am sure there is more i didn't try to think fo them all,my point is the TRINITY system is the best all you need is a developer to put some effort into the depth of the game systems.This means by even improving the VERY superficial character creation systems that games use.
You should have class properties,racial properties.There should be several variations of gear so that players can achieve their own personal character design.There should not be that ONE TIER set then you are able to take on the top instance bosses,that is not game design that is lazy design.
So as to not confuse that SAME depth should go into the mobs Ai and how mobs react,example can they see well or hear well,do they react to injured players[smell blood],exampel the undead.You need that same depth in weapons,most games you just grab the weapon that shows the highest stats and that is it,again LAZY design.You should have a in depth system for example blunt weapons and guns do more damage versus thick boned creatures and piercing does more versus weak flesh creatures.then you need a whole accuracy system,flying creatures should have higher evasion or perhaps cat like creatures are more evasive.Some creatures like undead cannot be charmed or slept because they have no brain.
it is all easily doable in each character and mobs information and data systems.
Right now there is a horrifying trend to go EASIER/SOLO/FASTER MORE hand holding,END GAME and generic combat design all with spamming hotbar icons.