+1
Knocked Down Prone shouldn't make you lose your turn or concentration. Even if you don't have the required movement (half your total) to stand up, you should still be able to use actions & bonus actions while prone. You should even be able to move while prone, at half speed (techincally every foot of movement costs 1 additional foot, so it'd be 1/3 speed while in difficult terrain, not 1/4).
We should even have an option to freely (or maybe costing 5 ft of movement) drop prone, as doing so will force ranged enemies to attack us with disadvantage. Make your ranged attacks -> drop prone -> ranged enemies attack you at disadvantage -> stand up next turn -> attack -> repeat. It'd be a nice tactical option.
