I agree that this would be a good change. However i think it's ignorant to say that shielders are easier to shoot then other classes. Shielders are my last choice to shoot at, however I do shoot at them when i have the chance since they are the very first ones to feel they are safe and start to be careless. The few players that are aware of their surroundings and have a shield are incredibly difficult to hit. They can only be hit if they are engaged with another player or knocked to the ground by cav(and sometimes the passive shield still blocks it from the other side). Shielders get so annoyed when shot by ranged because they've invested points to counter this specifically. But it doesn't mean it's a hard counter in all situations and when you're not using it correctly.
The whole reason ranged shoot shielders when they can is because the fact that the shield is so hard to shoot around and you do not want to have a shielder in the mix when fighting multiple people in melee. Bolts used to go through shields at about a 30% rate. And shielders felt like it was a 50% chance. Currently it happens once in a blue moon, I would say 2-5%(and that's really rare when the average crossbowman doesn't get that many shots off). When the player looks the other way or is dumb enough to try and attack BEFORE the melee interrupt happens, they get shot(and EVERYONE does this lol). Sometimes I shoot at shielders heads at long range because they are looking everywhere, and the bolt hits right when they look behind themselves. DONT LOOK AROUND IN A SHIELDWALL, use Freelook. Wait, no carry on so I can keep shooting you and making you think that your shield is so useless. Believe me when I say a player without a shield is far more screwed then a player with a shield vs ranged.
I've played a shielder, I've been there. And it's not a hard class. Almost every person that has started playing the game that I know of switches to shielder because they cant block to save their lives. This gives them the ability to last more then one attack in combat, which is a good thing. I would venture to say, in general, that shielders are the worst manual blockers when looking at the overall population. You always have the exceptions like San and other good players who are shielders. But really, how quickly does the average shielder die once their shield breaks? It is incredibly frustrating to me that you can take a "bad" player in crpg and he can just hold block and s key to his hearts content vs a "great" player in crpg. There is no other tool in the game that completely shuts out another player's attempts to damage them with only holding 1 button.
As stated this change would be a counter unto itself because of players that are not aware of what their shield is doing will get counter directional slashed/shot around their shield even more vs players who have played long enough to register visual queues. You may be frustrating newer players more with this change since they hardly know whats happening to begin with. But I think the overall change would be a very good one for the game. It would be a good thing for competent shielders. Giving them more of a tool vs ranged at higher levels of play, and at the same time balance how much of a hard crutch the shield is to players. As it is with 1h you must block far more then your opponent, even back to back to back before you even get to attack once vs polearms especially. But there is a reason to why the player has a 1h weapon, and a reason this is balanced out by the benefits from it. Whether it's because they get to use a shield or a ranged weapon. Angles, footwork, and weapon length play such a huge part in this game that they blur the lines of balance. So much so that only very experienced players can see that the game is actually pretty balanced.
If you are not pressing right click at that moment, or looking within a 89 degree angle at your target, your forcefield is not there. It's as simple as that.