A very good idea that will take quite a bit of development time and SE has higher priorities right now. Scaling a dungeon isn't like updating your facebook page, it will take a lot of time and effort but SE clearly has a ton on their plate. After all 90% of their player base are all crying for 1,000,000 different new features and wondering why SE can't produce a matured 10 year old MMO within a few months.

A lot of MMOs do this in the long run, it will take time but I'm sure you will see it.