This would probably make it harder to play lancer and that's a good thing.
But keep in mind though, that this would in no way affect the bad lance players. So it would not be a nerf of lancers in general.
They would just keep on using the same side each time and also make use of couch lancing (which should not be restricted to one side).
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My view on nerfing in cRPG
If you want to nerf something you should do it by making it harder to make the most simple attack move.
This will directly affect all players, no matter the skill, it will nerf the class in general but the better players will still perform well.
The sad thing is that most nerfs doesn't affect the bad players. For example lance angle, jump throwing, accuracy etc.
What happens is that the gap between good and bad players decreases making the class easier and less fun to play.
Instead, make it harder to play the game in general and then add more capabilities and attack moves. Don't restrict, remove or make things less deadly.