Make him live up to the contract...it will cost 4x's as much to add it later.

Yes, written in the contract. He eagerly said he would fix it. Before I posted I spoke with a nephew who is a Building Supervisor for another major builder. He says from a personal standpoint he is not a fan of the floor outlets because it can be in the wrong place when you move furniture.

Plus I am concerned about cutting up the slab.

Even when planned in, floor outlets are never in the correct place for the reason you speak. In a recent project, my clients and I took extra care with planning our floor outlets, in the end they had to be slightly modified due to floor joists. On top of that after moving in, they decided to place their furniture in a different layout then we had planned.

I vote fix it now. How big is the space? If it's a 20x20 room, do you really want to run extension cords across the room to light lamps, charge the laptop while you're on the sofa, etc?

Thank you everyone. The builder plans to correct it, so I won't say anything and let him correct the error. Thanks again!

He's lucky you're not polishing the concrete.