I'd rather eat my own toenails than play Medic without crossbow, tbh. Without the bow, it takes too long to heal and everyone dies in the time it takes to get a Soldier to 200. More importantly, Medic is literally a dog on a walk with no crossbow. You just click in the general area of a teammate, leave the beam on (don't even need to be looking at the patient!), right click when it's important. No other mechanic. Landing a good crossbow on a teammate or enemy is fun! Beaming is... not fun. (But Medic is also not fun in general)
IF you were going to nerf the Crossbow (and I'm not sure I'd want that), you'd need to do this:
Increase holster + equip time so that when you see a player get arrowed you can jump their med and he can't uber or saw you.
Increase range needed to heal. Implement crit heals for bow. Decrease minimum heals.
The goal should be to create a long range heal solution that is superior or equal to healing with the beam for a few seconds, but can't just Undo the last 15 seconds of damage for a Demoman.