This and names on the back were the only two things we should've kept from Superleague.I'm all for squad numbers, though I'm happy for 1-99 instead of 1-30. 1-99 also gives you the opportunity to add Reserve Grade and U21's as well if your club goes that deep.
Like you said, the numbers rarely mean anything on game day: positions where two players play (2nd row, wing, etc) already get a choice of 2 numbers to wear - who can honestly tell me which side of the field these days is 2 and which is 5? Once the reserves come on the numbers almost become pointless outside of identification.
It also helps the players create a brand for themselves around their chosen number, and the club and player can create additional merchandise. I like putting the official numbers on the St George jerseys I buy, but it's a pain in the arse if they move around all season. For example, I had 3 put on my Dragons heritage jersey because that's where Jack Bird played that day and he was having a great season for us. But the rest of the season he also played 5/8, fullback, second row and lock. I do that with a standard Red V, it could of been Bird, Lomax, Ramsay, Beale, Amone, and probably others I'm forgetting.