To me it sounds quite a lot like something Monte said about complexity, that I disagreed with at the time and disagree with now.
His argument, as I recall it, was:
- New players will probably start at 1st level, and should have the easiest-possible entry route to the game. (I agree with this.)
- As they play, their PC will gain levels. Meanwhile, they will both become ready for more complexity, and will probably find it desirable. (I agree with this also.)
- Therefore, complexity should rise with level.
I disagreed with this conclusion, on two counts.
The first was to do with higher-level PCs. The problem is that each player will almost certainly reach a point where they say "that's complex enough; no more, please". This point will differ from one player to another, but each player will probably have a maximum threshold. But if complexity just keeps rising with level, this means the game will reach a point where, as a "reward" for continued play, the player finds his favourite PC is no longer fun. Which obviously isn't good.
The second count, and the one that's more relevant here, concerned what happened in the second campaign, when experienced players start again at low-level (and probably 1st level at that, since that's still where most campaigns start). Such a player won't want their character to just be "Dwarf Fighter", but will want the game to give them more options.
Now, the solution of "start at 3rd" is okay, as far as it goes, but it doesn't help the mixed group where the experienced player and the newbie are together - they probably want the same level, but different complexity.
I believe the better solution, and one place where modularity gives clear benefits, would be to present the classes in their simplest form in the Basic Game (and maybe the PHB). Then, in later spatbooks and/or an Advanced Players Guide, present the classes in a much more flexible manner, showing all the building blocks and allowing any and all of them to be switched out - perhaps even to the extent of offering a point-buy option at the top end.
That way, you can cater for everyone - the new player gets the simplest possible 1st level. The player who wants complexity to plateau can probably arrange that. And the guy who wants all the bells and whistles can choose that option as well.