Eldrich Blast is probably as powerful as a cantrip can ever hope to be and some occasional extra utility in the form of extra spells can helps not to mention that as a charisma-based class the warlock is implicitly a good fit as the "face" of the party.
The strength of the cantrip: a d10? Then you can elect to use an invocation slot to add in your attribute bonus. Now it's up to the power level of a heavy crossbow. Great, I guess. Shrug.
At level 5 you get 2 blasts with 2 Charisma bonuses applied, and 2 Hex dice applied.
Then in the current patch Agonizing Blast applies to BOTH the Blast and Hex AND Lightning Charges if you have that item; bug or homebrew is unknown right now. Heavy crossbows don't get the extra attack at level 5 unless you take a feat, and have a Strength requirement, and need Dex to get a to-hit bonus. Warlocks just need Charisma.
Warlocks don't get great spell flexibility precisely because EB is hands-down the best cantrip in 5e. The class just feels a little lacking in BG3 because we don't have many sub-classes or class features yet.
