The whole system needs an overhaul in the way of compensation.
However, we arent losing kids to rivals, ie they arent going to a Villa, or a Sheffield Wednesday, etc the ones we are losing are going to elite world renowned clubs - Chelsea (Brown), Liverpool (Dhanda and Sinclair), PSG or Barca (Barry).
Not all the clubs are known for great youth development but they are world class clubs and whatever level, youth or first team, if a Liverpool or PSG come calling it turns your head. With the exception of Brown none of these players were with the first team, the clubs are signing potential, signing them at 14, 15 or 16 and there arent many lads of that age playing first team football so i dont think we can be too criticial of the Albion here.
They offered Barry a three year contract, apparently on very good terms but as others have said financially going to PSG / Barca he will be setup very well for his future and the coaches and standards they have you can only learn from if you apply yourself, if he doesnt make it there he can step down to an Albion, etc.
Our best potential players are likely to get picked off, thats just football in general at all levels, so we have the next level down, the likes of Field, Harper, Edwards. What the club have to do for those players, and something they do have to improve, is show them if they are good enough there is a pathway for them to the first team, but if not ready they go out on loan, not playing under 23's football for seasons at a time.