I was under the imression that everything could be customised from the race and background, appearance, class, stats etc.

When respeccing companions, you can't even change the stats where the +2 and +1 are applied - like Shadowheart is stuck with +1 in strength.

In Bg1 / BG2 you could just play a local multiplayer game and fully customise a full party, there wouldn't be any story but by the point players got around to doing that they'd already beaten the game like 100 times over or so.