So even if they get better, the shot will still be harder and there is a point where it won't make sense. Maybe forever guys will just get better and better at 3's and will be shooting 50% some day, but I don't think so.
The problem with just letting it go out of bounds is that you now have a portion of the court that you don't need to guard. Long twos are exactly what you want an offense taking so you would simply leave them wide open while packing in the paint. Guys would rarely go there on offense and defensive players would be very slow to guard those offensive players.
To me basketball is still the best when it is a free flowing game. Great passes, great shooting, great drives. I think you need them all. Just my opinion though, it would be interesting to see what happened if we did it your way.