Handy to toss on a bus?
Oh, hey, it's HD44780 compatible, isn't it -- command set and everything? Though a lot slower, at 600us max per instruction... which is pretty disgusting to write 80 characters in one go, that's a 20 FPS refresh rate? Yuck... Hopefully it can go faster on some operations, but who knows...
So that, and they've tacked on SPI too, which is nice.
I recently did a project with a parallel bus to RAM and DAC; the display was HD44780 based anyway, and I didn't have many spare IOs after allocating the bus, so it was a natural fit. It would be hard to do serial (DAC, display or other things) on that particular project, but with more pins available it would've been fine.
If on the other hand, you're doing just a lot of stuff with the GPIOs, and can't easily afford to multiplex them -- saving a few pins here and there with a serial bus is an excellent idea.
Tim