So in that case the selling point becomes utility/versatility for a minimal loss in combat capability/DPR?
I think the big disconnect is that you seem to be viewing classes, and the level of appeal to play them, based solely on a mechanical reason. for most of us, that's a non or minor factor. Classes are more than just a number; that's why they have several paragraphs in the class description of what they are like before you even get to the mechanical bits. In a role playing game, the role playing aspect shouldn't be ignored.
But let's set aside that for a moment and talk just about the mechanical bits. You seem to assume that there is a loss of DPR compared to an EK or paladin, but you're only looking at melee combat. There are a
million different scenarios where combat comes up, and melee is only a small part. Not all of your opponents are going be lined up in a neat row for you to attack, rinse, repeat.
for Example:
* when outside and opponents all over the place, some over 100 ft away, I can hit them each round with a call lightning while the EK or paladin has to break out a bow, and God forbid if they spec'd STR like you mentioned above, or they're going to be spending their actions running around, not attacking squat
* Even if my one attack roll does only 2d8+X damage compared to an EK or paladin's 1d8+X (x3 attacks), I'm also doing 3d8 damage to 2 or more attackers who happen to be within a 15ft radius of me due to spirit guardians (I've hit up to 6 opponents with this spell in a single round before).
* The paladin can add a few extra D8 when he novas with divine smite? Big deal. I'll drop a destructive wrath, max out the thunder damage with my channel divinity, for way more damage to EVERY creature within 30ft that I want.
* for Sh*s and giggles, I can drop a flame strike, insect plague, storm sphere, or whatever else I want.
So no, in actual play, I don't feel like I'm giving up any combat capability. In fact, I think I'm more capable in combat because not every combat round can the EK or paladin do what they want because the enemy isn't in perfect position, while I have many options to always hit the bad guys where it hurts. I think you really need to look at what schools of magic a EK can cast from, and how many spells at what level they get too. You might get one or two 3rd level spells while I'm dropping level 5 and 6 spells a lot more often, on top of being good at melee combat as well with just that one spell (spirit guardians)