I'm a fan of squad numbers, following the ESL approach that your starting 13 gets their relevant position numbers, and the rest of the squad goes from there.
I think it adds some prestige to the numbers when a player can only a position number at a club, especially for a number of years. For a young halfback coming up at Penrith, you want to be the one who takes the number 7 jersey off Cleary for example.
As for people complaining about say number 45 taking the field, it never use to be an issue when we use to have Reserve Grade, President Cup, etc. When you saw one of those higher numbers take the field, you knew it was someone who had come up from one of the other competitions. I'm sure very quickly people would view it the same way.