I'll be a naysayer here and argue rather that a large expansion of possible NPCs rather than a raise in party number would be far more preferable, particularly with interactions between NPCS (Like Shadowheart and Lae'el and how Shadowheart leaves if Lae'zel joins) would be highly preferable to me.
I have absolutely no idea of what makes you think they would be mutually exclusive. If anything these features would go hand to hand.
Party control in Baldur's Gate 3 is a complete mess that begs to be addressed. SAY NO TO THE TOILET CHAIN