If you have any kind of bonus point system, it will create alleged anomalies.
If you award points for big try hauls, then of course there will be a flip-side. In this case, draws aren't worth very much.
(In practice, the funny-shaped ball game creates so few draws that it's not a big issue. In the sensible-shaped ball game, 3-points-for-a-win makes a big difference to tactics.)
My personal preference in these round-robin systems is to have Result-between-the-two-teams as the first "Decider" - in which case Wales could not finish behind England.