D&D 5E Warlocks seem pointless

[Mallus]

Seeing as a lot of Warlock DPR actually comes from getting hit a lot (Hellish rebuke and Armor of Agathys) and they have a fair few class features and spells that grant temp HP or resistance, this latter aspect is an intentional feature of the class IMO.

This observation is spot-on. By mid-level, a melee warlock will consistently be doing around 30-40 pts. of damage per encounter, on their opponents turn --ie without using any of the warlock PCs actions-- if they use Armor of Agathys. They gain this benefit by virtue of being easier to hit. Once the armor's gone, they can either re-cast it, if they have a slot available, or retreat and blast.

Or you go the opposite route and build a lower-damage melee warlock meant to tank/draw melee attacks, with a high AC and a spell like Mirror Image running.

 

[Joe Liker]

Because you got interested in the NPC who gets waived under your nose as an oddity in the middle of Episode IV of Hoard.
Get the jump on him, he's toast. Just don't get caught.

I was level 3 or 4 by then, and had already chosen my pact.

(Also, as a good-aligned party, stealing the spellbook from someone who has never wronged us isn't really an option.)

You see what I'm saying? I chose the pact BEFORE I met the wizard. When I chose the pact, I had every reason to believe rituals would be sparse.

In fact, I still have every reason to believe it. I don't know how many rituals are in the spellbook you're talking about, but it's probably not a huge number.

Are there many more spellbooks to grab later on in the adventure? I don't know/care at this point because my warlock can't use them, but I'm asking out of idle curiosity.

If the answer is no, I'm still of the opinion that taking the Tome Pact would have been a bad decision.