Tino_If your think that med turns into only hold M1 if you get rid of arrows I don't know what to say other then your blatant inexperience is showing. The xbow does add some mechanical skill to the class yes, but it also removes a huge amount of brain power that you used to have to use on med. Before the xbow you had to actually choose heal targets, who deserves the heals and what class is best in what situation, not only that but if you were decent at aiming needles you actually added a lot of DPS to a fight that could win the game for you. Now you just sit back, bait your team and hope the +130 arrows hit during big fights. Along with that the #1 issue new medics have is the fact that they use arrows way, way too much because they think they are good with them, when in reality they are not. So not only will the removal of arrows bring back some of the mind games to medic but it will also help the lower level players because it forces them to actually heal and to actually think about what the fuck they are doing.
I would argue that there is more potential for using brain power with crossbows.. not only do you have to worry about which heal target is the best within team fights, you need to know when it is best to use the burst heal and when to use medigun - people act like arrows are always better but that isn't the case, the most optimal way of healing is to use both of them together to maximise your heal output, and if you can manage the HP of multiple players at once you will have significantly more impact than other medics, and I feel this is something that ive only seen top prem/invite medics do on occasion.
Its also most efficient if people cycle their heals and have some form of rotation to use buffs most effectively, and this is something that teams need to get better at, not just medics, as this is an aspect of team play that happens to be directly influenced by one class. There is also the fact that if you miss an arrow you will be sacrificing medigun heals for that duration. Basically the optimal type of healing that you are outputting as a medic depends on multiple factors like which classes are fighting, which sources of damage different heal targets are taking, which players are in active fights and which aren't - and this stuff defines when to use crossbows and when to use medigun to play optimally.
People say it makes medic more fun and simplifies the class, but IMO it raises the skill ceiling significantly and adds more depth to not only the decision making of individual medic play, but also to the dynamics of team fights. There are a lot of cases in 90% of medics that this all gets ignored because at lower levels of play it seems like going for arrows is always better, but in high levels of play going for one risky long range arrow could lose you a team fight if you miss it.
All this being said, i do think that crossbow is OP in its current state, but I don't think any proposed changes I've seen would correctly balance it without simplifying these dynamics that it adds. I think perhaps having a fixed arrow base heal of 75 HP, and having that increase not with distance but with critical heals could work. This would also reduce the impact of arrow building as you would gain 5% from each arrow, and you would need to arrow build properly (not as a lot of current teams do it) to actually gain something from it, thus further rewarding coordination.
Edit: this would also mean you could still put out 150hp arrow heals after 5s of the heal target not taking damage, regardless of range, and I feel like that is a fair trade off with heal output - if you and your players can manage their heals and rotations together it would make sense to be rewarded with optimal healing.