How many of these 2.0TB SATA drives are you going to purchase to do the same number of random cache miss IOPS that a single SSD can do? The math does not lie, applications are out there that can gain massive performance improvements and save money at the same time using SSDs. It's so easy to say hey, re-architect your application. Guess what? Mission critical apps grow organically and are not always optimized. How heavily used will your application get before even your optimized IO creeps into the realm of "I/O patterns so messed up that today's horrendous SSDs actually lower your cost per I/O"? How much money do you think the bank/nation-wide retailer/wall street firm would need to spend to "rethink their information architecture"? Not to mention power and cooling of a room full of short-stroked 2TB SATA disks vs one cabinet of SSDs.
SSD is not gaining traction simply because it's a buzzword and commands huge profit margins (both are true). It works. It solves real problems. In the right cases it saves money. If you spent some time in a larger organization I suspect you'd change your tune. You're comparing 2TB SATA apples to 256GB SSD oranges. Both may be fruit, but they're not interchangeable.