Higher write speeds also mean lower power draw for the flash memory. If the user saves data consuming only half of the total user capacity of the drive, the other half of the user capacity will look like additional over-provisioning as long as the TRIM command is supported in the system.
The biggest barrier that Solid State Drives have faced over the last five years is that they have been extremely expensive, and extremely low on capacity.
Wear leveling refers to the bag of techniques the SSD uses to keep all of the flash cells at roughly the same level of use.
So this a rare instance when an amplifier — namely, Write Amplification — makes something smaller. A SandForce SSD controller has a small amount of working buffer space instead of a big multi-megabyte pool, and as data comes in off the bus, the controller divides the data up into small pieces and compresses them, using some manner of hardware-assisted lossless algorithm, because speed is critical.
The data coming in is still chopped up into blocks and deduplicated, but SandForce-powered SSDs typically aren't as fast when writing compressed files. It protects the drive after an error occurs, so in a way it is similar to RAID protection, but on a single drive. Technically, you already know how much you wrote from the host, but it is good to have the drive confirm that value.