The FT lanes do have platforms as you describe them. In fact the platform is two pallets stacked one on top of the other and the whole topped off with a piece of astroturf. I know that many courses don't have defined lanes, and even those that do will often shoot from a bean bag on the deck. The down side is that right handers' feet end up churning the ground just where a left hander wants to place his bean bag. And being a left hander I have issues with that.
Also we have a number of members whose mobility is not 100% and they find it a lot easier to get up after shooting a lane if they start at eight inches off the ground. The astroturf is non-slip and negates the old argument against wooden pallets.
But your point is a good one, and I see no reason why we couldn't use two pallets on edge to create a shelter at each lane.