EK was one of the best players in the world in his prime, that Ottawa team taking what ended up being 2x champion Pittsburgh to Game 7 OT was a testament to just how great he was. And plenty of players of that era have echoed those sentiments. Not many who could do what he could do transitioning from offense to defense, even a guy like Hughes who is amazing at doing that doesn't really compare. People kind of throw around the generational label to easily (like Eichel isn't generational), I think EK really fits the label of generational, he was that good for about 6-7 years.
OEL was never close to that level and makes no sense for the Kings now, regardless of what the cost is. He turns 30 in a month and his play has declined significantly from his prime years, also an $8.25 cap hit with a full NMC for the next 6 seasons? No thanks, that is the type of deal that could really hurt the Kings in say 3-5 years when the team might be good again and they are carrying that kind of cap hit on what could easily be a replacement level player by then.
Arizona is going to have to retain a decent amount to get any kind of value from a team with a 2-3 year window.