I doubt they would balance the game to require strong summoning dolls.
In Divinity I never used summoned creatures, and had lots of spare skill points throughout the game. It is unlikely my planned warrior/archer combo would need as many skill points as a mage/something party would (maybe, have not looked too close at the archery skills, since they were not available in the demo), so even if summoning dolls prove very useful, I should be able to spare a couple points.
