E-readers would be good if they were robust enough. All the trials using ereaders so far have shown that current devices aren't nearly robust enough, nor repairable enough, to be useful.
E-readers also suck for figures and formulas which are indispensable for any comprehensive education. The most readable textbooks can only be rendered on a big high-res display, on iPad at least.
Cheap 10" tablets are definitely easier to make than cheap 10" E-readers, though.
