A real shame. A crawl, walk, run path would be very helpful it seems.
5E
could have been designed that way, in three "modes" so to say: easy, moderate, and hard (for lack of better terms).
In easy mode, your choices and decision points are minimal (if hardly any... think 1E). You still have all 20 levels, but you see a lot more focuses and linear growth. Game focus is really on the adventure, not the character--whose growth is less. In some ways, this is like the Essential Kit or whatever in 5E, but maybe even simpler....
In moderate mode, some more optional features and mechanics are used, like subclasses and feats, so there are more decision points. The additional features add more power and choices for what your character can do at any time. Again, all 20 levels, but focus is on paths and choices. This would be like 2E with kits and such in the later splat books up to 3E or 5E. While the game focuses on the adventure still, more attention is paid to character growth and individuality.
In hard mode, you have the works. Complex mechanics derived from options and features that require more time to resolve, but offer a lot to the players and DMs. You have feats, multiclassing, prestige classes, and more probably. For most players, a lot of time would focus on planning your character's growth, what you want next, etc. It would adopt very easily for more power-gamers in general. Something like Level Up maybe? Or even some aspects of what 5E2024 is?
Finally, the "crunch factor" would be fairly separate (if possible...) in that you can have more features from the hard mode, but resolution could be handled more quickly in the easy mode if you don't mind "hand-waving" or "glossing" some things over.