SSDs are actually becoming very common in datacenters. If you shop around for hosted VPS solutions you will find a lot of them offering SSD storage as a premium option. However, that wasn't always the case. When SSDs were becoming popular they had two major flaws:
They could only be written to a certain number of times before failing and, while it varied from drive to drive, the number was fairly low.
The drives put out a lot of heat which made them problematic in large arrays.
Those two things kept them out of the server room for a long time. In the last few years we have seen the temperature of the drives come down significantly and the amount of writes before failure increase. That allowed them to creep in to high-end datacenters. They were really popular for OLAP database scenarios which are almost entirely read operations and benefited greatly for the decreased seek time of an SSD. Now, we see them used for everything including general OS drives. All that being said, though, any admin worth their salt builds it in to their budget to replace the SSDs every two years. The increased cost of replacing the drives is more than compensated by the improved performance.
As for the overhead created by storage pools it is actually very small. Every read/write operation passes through the Windows Hardware Abstraction Layer (HAL) on its way from the OS to the physical disk. The redirection occurs within the HAL so it gets great performance with minimal impact. I wouldn't use it on a heavy OLTP database server, but on a home media server you won't even notice it.
Hope that helps,
Don Pezet
Host, ITProTV