Yup. I believe the DD saves storage is over 12GB now, that's compressed and extremely minimally stored using a bunch of tricks. The dailies for just a week are something like a few hundred megs and that with not too many people playing anymore... We'd be storing loads of data that wasn't really useful to anyone - how many times would that be accessed?
The other element to consider is that we'd have to deal with much slower auth queries on that DB due to size (unless we did a whole bunch of weird shunting of data when it moved out of the current day, which is more load on our server), we had to put a lot of time into just getting things working as "fast" as they do now... I doubt we'd be able to afford the servers we'd need to keep a much more expensive implementation up and running right now.