I see one problem to this though : we won't be able to run stuff at 15 MHz. Not a big deal since most ASM games/programs run at 6 MHz, but the 83+SE and the 84+ run TI-BASIC at 15 MHz.
How many cycles does it take to update the whole lcd on the CSE ? And in 160*240 mode ?

I doubt this would be much an issue, though, because for over a decade, most people ran their games at 6 MHz anyway. Of course this would be problematic for games that are 15 MHz-only, but I think it would be better than nothing in general.

Plus, by displaying fewer pixels (eg scanlines or smaller screen), this gives a speed boost.