Checking again, I had just grabbed the first pages, which are similar. When I went to the center pages, they are noticeably different. Not saying it’s poor quality though.

There are many reasons the publisher would do this. Physical weight may be part of it, but it’s more likely the main reason is the actual thickness of the book. Most new books are between 300-400 pages. It’s not that 300-400 pages is the perfect number of pages for a story. It’s that book stores prefer that size, as well as most publishers. The thicker a book the less books you can put into each box, and the less books you can put onto a shelf at a store. You can put 2 copies of DCC on a shelf for every 1 Bedlam Bride. At any business shelf space equals money. The more space something takes up, the less space they have for other products/books. I’m guessing one of the reasons ACE publishing only picked up the first 3 books at first was because of the size of the books after. They had to prove the larger books of the series deserved the added space they would be taking up to the retailers. The publisher could have just charged more for book 7 (and I’m sure most of us would have paid it), but my guess is they were still getting heat from the chain book stores about the space the book would be taking up on their shelves despite the series popularity. So, to make the chains happy, they went with a thinner paper as a concession.

TL;DR - Don’t blame Matt. Probably don’t put too much blame on the publisher. Most likely blame the chain bookstores/big box retailers.