HMe has it right with #3. Its all about power. The "key suppliers" could care less about performance enthusiasts. They design for the big OEMs first and foremost. Since the OEMs have already designed the power and cooling in their servers for 20Watt 3.5" drives, they can't deal with the higher power a >=20Krpm drive with large platters would take. They only alternative would be to use small 45mm or less platters and the capacity would not be attractive. Now that flash is becoming more viable, 20krpm drives become even less attractive since they'd be the same capacity, have fewer IOPS and be almost the same price.