As a warlock player I can tell you this is not a requirement to making a fun, useful, warlock. Nor is EB blast itself.
Wow. What order to unscramble this in?
A) Simple blaster Warlocks are already a thing. And it doesn't get any easier. Step 1: Choose Warlock, Step 2: Select EB. Step 3: Select the EB modifying invocations.
Congrats, you've created the most stale, cookie cutter, damage machine you can with the class.
B) Why isn't EB a class ability? It is. It's an option you can take under the cantrip heading. You have to CHOOSE it because there's all types of warlocks out there, not just damage dealing ones.
Why aren't EB modifiers built right in? Again, choice. And clearly the designers intended you to only have access to a handful of spaces in wich to customize your warlocks power set. Wich brings me to....
C) Those invocations you think should come with a price? They DO. A heavy one. Because if you take one of them you're not doing something else cool. So choose carefully.
Of course this does depend upon how you look at a class. If all you see when you read the entries is x damage? Then you'll never understand how cool something like beast speech can be.
I agree wholeheartedly. In fact, I have played three warlocks (sadly only to lower levels! but am hoping to truly stick with the next one much longer) and they are all blade pacts.
I refuse to take boring "pew pew" for various reasons most involving it is not as fun. I like misty visions at will and so forth. I was thinking about the fun with mask of many faces and the utility of detect magic at will. For me, agonizing blast really helps me survive until I get that pact weapon for a couple of levels but I am more intrigued by repelling blast and its ability to disrupt (maybe disrupt right off the ledge)! At that point (3rd level), I like a switch to a more melee oriented stance for the purpose of fun! Also, EB is at disadvantage with an enemy in front of you is an issue. And why doesn't anyone see the advantage of EB as the enemy closing with the fun of unsheathing a gleaming blade when in close proximity. I think these are complementary and are not as is often suggested exclusionary! The power of the combination is great if that is the concern. And better than one of them alone in raw punch by my reckoning.
The real power comparison really should be between the pact features of tome and blade or even chain. And these are much harder to quantify. They are merely different...
I think the power problem is only a problem if you compare raw melee to raw melee (Warlock vs. Fighter). But this does not account for spells, cantrips and invocations and frankly flexibility! It would be absurd design for a warlock to fully match the fighter in melee and then also have warlock goodies, right?
I am not saying the OP changes are absurd btw merely the conventional wisdom that the Bladelock must fill the role of primary and not secondary heavy melee hitter.
But frankly, after confusing and screwing with the enemy, disrupting and damaging and maybe charming them, isn't two attacks with thirsting blade and lifedrinker (maybe with a third attack from polarm master or GWM) "enough?"
I wonder sometimes if we have not fallen into groupthink with this class. In fact, we only have to have heavy armor if we are trying to fully replicate fighter. Rangers only have medium armor for example. Since I play with feats, Variant human allows for this at the start...
But I digress.
I will say this, I do think one additional spell slot at least would be nice and not overpowered. I might be willing to take magic initiate to get one and even (shudder) multiclass to get few extra spell slots. Two burn really fast.
So what I am saying is that perhaps the conundrum is the opposite of what some propose. Perhaps the melee side of things is sufficient but the magic is just a bit underdone.