So I'm no economics major but I am pretty sure that combating a fall in demand by raising prices wasn't what I learned in Econ 101.
Stamps havent really kept up with inflation. Stamps should be about $1.00 if they did keep up with inflation. They were 5 cents in the early 60s. Pretty much everything has gone up in value 2000% from cars to houses. Stamps have only gone up in value 900% since 1960.