Is it practical to intentionally stall an aircraft to execute a fast, controlled descent?
It isn't practical for a number of reasons:

Intentional stalls are inherently dangerous. Stall-spin accidents are a major cause of accidents, stall recognition and recovery are taught specifically to avoid stalls.  Some airplanes have docile stall characteristics, but even those can still bite you. A Cessna 172 will drop a wing if mishandled, especially when heavy. Stall behavior at high altitude can be very severe
Some airplanes with a t-tail can enter what is known as a 'deep-stall', where turbulent airflow masks the tail and makes the elevator ineffective and the airplane unrecoverable
Situational awareness: dropping like a stone with the nose up does not give pilots a view of the outside, or see what mountain they may be heading towards
It takes time to do a controlled stall. You have to pull throttle and maintain altitude, degrading airspeed until you enter a fully developed stall. This isn't instant, in a light airplane it will take 30 seconds or so, I'm not sure how long it would be for an airliner at cruising altitude, but I imagine it may take a minute for a fully developed stall to develop and to get that high rate of descent, whereas you can be in a dive with a steep rate of descent in a much shorter time

Consider an emergency descent from FL400 (40 thousand feet) to FL100 (10 thousand feet) using the 2 methods: A dive at 8000fpm and a 'controlled' stall at 10000fpm, where it takes 30 seconds to get into a developed stall and high rate of descent:

60 seconds: the diving airplane is at FL320, the stalling airplane at FL350
2 minutes: the diving airplane is at FL240, the stalling airplane at FL250
3 minutes: the diving airplane is at FL160, the stalling airplane at FL150
3 minutes 30 seconds: the stalling airplane is at FL100
3 minutes 45 seconds: the diving airplane is at FL100

So, by these calculations the stall option saves 15 seconds to lose 30 thousand feet because of the time penalty to get into a stall in the first place. That's really not much, and considering the risks involved from the potential loss of control and spacial awareness it's simply not worth it.
Not only is it not practical, it's not necessary to descend faster. A high speed descent is required for a number of emergencies, a cabin depressurization being the most prominent one, but there you have emergency oxygen supplies which will last much longer than required, so a few seconds will make little difference to survival. With an in-flight fire or other emergency where landing quickly is imperative the limitation is not descent speed, but proximity to landing fields which determines survival.