I'm sure they'll get more in. My wife bought me a pair of each size last year, and they quickly became my favorite glasses. I'll be buying another pair of each this year!
Another site had a better description of the volume of these glasses.
The 12oz glasses have a 12oz "line" and are 14oz to the brim.
The 16oz glasses have a 16oz line and 18oz to the brim.
When I went to Fort Collins, where New Belgium is, I ate at "Rasta Pasta" and they had $5 New Belgium pints and you got to keep the 16 oz glass. They are really nice!