But Y'shtola wasn't even the one who thought about food. Unless I'm miss remembering. It was Vrtra and Zero was fine with both the "out smart the devil" bit with the name and having to wait longer for some sweet dragon aether.

I think her aether sight could still be a strain on her even if it's just the same aether pool one uses for casting. As I see it more akin to how at least back in ARR casting black magic was highly dangerous to do so without a soul stone due to what aether you tend to use while wielding black magic. Same sort of thing as to why there's a limit to how much a person can heal due to again where that source comes from. And why Sophie's mother died when she tried to actually raise a dead person back to life. We just haven't had something put enough of a strain on her yet to where she'd have to stop or put herself at a high risk. I could see it happening during our next trip into the void though unless they bring some of the new and improved Archon Loaf from the Cul/Alch Studium quest line.