Think you're suffering from amnesia, mate!
I've been here for 20 years and the price for all beer has gone up. In the resort where I live, a bottle of Tiger beer used to cost 60 - 65 baht in a bar - now it's pretty much a standard 80 baht in most bars. Same for "farang" food - a pack of pomelo used to cost 35 baht in my local supermarket - now it's well over 100 baht.
The price for Thai food has also increased - but not by as much, I will agree on that. The price for bottled gas has gone up from 300 baht to almost 500 baht, so I think your memory is playing tricks!
However, I agree with you regarding rental prices - they have remained pretty constant, but don't forget that 20 years ago we were getting 70+ baht to the British pound, so a 10k monthly rental cost you app £140. Nowadays, at today's rate of 44 baht to the British pound, it costs you £238!