Meh. SSD write amounts matter if you're running a datacenter. They don't matter to a normal user on a laptop/desktop using a browser. SSD lifetime simply isn't an issue, as the other commenter pointed out.

Also, from a more philosophical standpoint - this isn't Mozilla's issue. They shouldn't have to worry about conserving SSD writes. That's not their problem. That's the OS / Disk firmware / manufacturer's problem. If I want to write files to the disk at a very reasonable rate, I should feel free to do that.