Not really, although there are some possible hardware sacrifices such as CD ROM Drives, but if you are looking at their speed etc, I guess thinner laptops can compete. Technology is just fast rising as the others said.
It's nothing but making more advancements in the existing products that's all not not meant to decrease their efficiency. Before delivering a product, they do test it under various circumstances to make sure it can perform better than old one. Obviously cost may be higher for any new coming products in the market, it happens with the most of the products.
Ultrabooks tend to be quite powerful, actually! Their high price is justified by the processing power, the use of an SSD instead of a typical hard drive and materials of a higher quality. I wouldn't choose an Apple product, though.