It is useful! As expected, RAM and CPU consumption are major issues. Saving RAM by computing the data to send to the LCD line by line proved to only be possible for text and extremely simple graphics, even with overclocking. The timing requirements are far looser than those involved in generating video signals, but the refresh rate needed to avoid flicker is actually quite high, the LCDs are intended to be driven at 60 Hz. This leaves 260 microseconds to compute each line.

Digging around through some old parts recently, I came across an old Epson graphical LCD display that had on-board drivers, but no controller. The LCD is an Epson EG2401, reflective, no backlight, 256x64 pixels. It has drivers...one SED1190 driving the rows and four SED1180s driving the columns...but no on-board controller. The LCD is supposed to be hooked up to a SED1330 controller and SRAM, but since I didn't have such a thing, this LCD sat around in a junk box for years.

Character LCDs with HD44780/KS0066U-compatible controllers are a widespread standard in electronics equipment, and are readily available and accessible to the hobbyist. However, microcontroller I/O pins are a scarce resource, and these LCDs use a parallel interface that requires 11 pins for a full implementation of the 8-bit interface.