Hello Sewata
About weapons : what Larian did add to weapons is a special attack for each (Cleave, Pin Down, etc.) which is missing in 5e. It is a nice touch that 5e/WotC I think should consider, in order to give some weapons a little something.
In fact, the issues with weapons comes from 5e, namely a) shaky balance between weapons due to sticking to the tradition of past editions, and b) some weapons are subpar or you wonder why any player would use it.
In the case of the shortbow, you use it only if your class is restricted to Simple Weapons, and you use the longbow if your class has access to Martial Weapons.
Exception : some races, mostly elves, have downright access to the longbow.
You are therefore correct that there truly is no reason to use the shortbow if you can use the longbow.
Your suggestion is GOOD though : the shortbow could have a special attack in BG3 that is different to the one offered by the longbow.
