Xeviat
Hero
I think a couple of the level 1 features need to be shifted to the 3rd level Blade Pact. This reduces 1-level dips, and makes Blade Pact more viable for non-Hexblades.
I came here to say this.
Also, to address the OP's friends' points, or at least the few I thought were important:
Hexblade can't "dump" Str and Dex if they want to go with their Medium Armor. Medium Armor requires some Dex to have decent AC, and since it has weight you're going to want some Strength. "Dump", to me, means an 8 or 10, since baseline stats are typically around 16, 14, 14, 12, 10, 8.
I don't think the spells are super great. Shield is rough as a Warlock spell. It doesn't scale with level, so you're going to be hard pressed to justify spending a 5th level spell slot to cast a 1st level spell. Kinda rough. I wouldn't call their spell list "the best". The smites are nice and really help pact of the blade warlocks though.
The hexblade curse is, in my opinion, something that should have been worked into the Warlock class progression to begin with. It was kind of the warlock's thing in 4th edition, and to have that just become a spell was ... Weird.