I'm not one of our hosts, but I would like to hazard two theories:

One, she's still blind for the same reason psykers are still psykers, carrying their genetic abnormality beyond death. Toph was created blind, it's part of who she is and who the universe intended her to be, not something that was inflicted on her later in life. The universe is more mysterious than even the Gods know and the plans it has for people proceed even after the point of death sometimes.

Two, Toph could be un-blindificated if she wanted. Even in the absence of magical healing there are technological solutions. She simply chooses not to be. Being blind has never been more than an occasional inconvenience for Toph, as her earth sense gives her an awareness of her surroundings that puts even Daredevil to shame. Maybe she'd like to try this whole "reading" or "TV" thing sometime, but not enough that she wants to completely change something that's so fundamentally a part of who she is.

-Merc
Keep Rat