As mentioned by Avery, superstar luthier James Olson uses a 5 piece laminated neck on his guitars. He's doing something right as his current base price is a staggering $15k.....wish I had bought one back in 1997 when his base price was $4200
I'm sure the 3 piece neck is cheaper for Gibson to produce they are probably using up left over pieces of maple from models with solid maple necks. Though generally a laminated neck is actually stronger than a one piece neck. Also on the plus side wood which will probably get scrapped for being too small for a one piece neck is being used up. Taylor does a similar thing with their 3 piece neck design much less waste and a stronger neck.