Yea, approaching Zelda would be scary. But literally no one has to. Even characters without projectiles just sit in a certain safe range, punish her once, and then she has to approach.
Lightning kicks are actually pretty devastating, if you can learn to land the bair you can really do some damage. I always thought she'd be better off with the same bair to serve the purpose of crazy strong punish and precision spacing, and palutena's fair. Having a redundant fair/bair with those properties is really ****ty, as she doesn't have a proper aerial spacing tool. Most characters don't have a fair and bair which do the same thing, so why does a character with a more situational aerial get stuck with a duplicate? Its pretty silly, and I don't think Zelda's would mourn the loss of fair. If you need fair, you're better of RARing bair and getting a stronger hit anyways. And the only advantage of fair is slightly less landing lag, which is irrelevant because if you sweetspot it you'll be fine and if you don't you're gonna die...
As for Doctor Mario, he always seemed like a superior Dark Pit/Pit situation. You use Mario for most MUs, then you pull out the doctor when certain traits would benefit you in a certain MU. Those being matchups where you need superior edgeguarding, damage per hit, shorter SH, or kill setups, instead of mobility and combos. When you don't want to play a Mario ditto, Dr Mario is a great alternative because you win bair trades convincingly and the low shorthop is actually a nice advantage in a SHFF aerial battle. Much like Melee, the nonspiking fair is actually an advantage in most situations, especially clutch situations where you get a surprisingly early kill with it, as it is actually pretty damn powerful for an aerial, especially with its speed. Of course, being more different than the pits means you need to dedicate more time to learning the nuances of playing the doctor, as he plays pretty differently, but it can be rewarding. A good Dr is pretty strong, he just has problem MUs. I believe he should be higher on the tier list, definitely.