Hussar
Legend
What I'm saying is that currently 5e feels and plays like a vastly different game than 4e.
We seem to agree on that any conversion document needs to make comprehensive changes and not be afraid to make deep alterations to the 5e game and its gameplay to be successful, if the measure of success is "now I'm using the 5e chassis and it feels like 4e".
Like you, I don't see this happening if all they plan is a perfunctory mimimal-effort kind of document.
For AD&D or PF that will probably be helpful to some, since the underlying gameplay isn't completely dissimilar.
But 4e to 5e? Not a chance.
To say it with other words: if the conversion doesn't piss people off, it won't be successful ;-)
Again, I find this baffling.
AD&D had none of the rules that you find in 5e. About the only commonality is speed of play. 5e plays at just about the same speed as AD&D. Cool. It's light years faster playing and simpler than Pathfinder or 3e. Good grief, you can't play a large swath of straight, 3e PHB classes in 5e. I want to play a summoning wizard... oops, sorry, nope, not happening. I want to play a 3e Druid with a scaling pet ... nope, not happening. Good grief, 5e has teleporting paladins and flying barbarians. That's about as far from AD&D or 3e as you can get. I can play a spell casting monk in 5e, something that has never appeared before. My Battlemaster fighter has encounter powers. What is the 3e equivalent to that?
What underlying gameplay is similar?
See, I go by the character sheet test. If you can hand the character sheet of one game to a player of another game and he or she can sit down and play, then those two games are close enough. A 1e character can pick up a 2e character sheet and play without any real difficulty - there's a few hiccups but not much. A 5e player can look at a 4e character sheet and find more similarities than differences. Saving throws are different of course, and the numbers might be a bit different, but, not too much. It's not like you have stats in the mid-20's or 30's on a 4e character sheet (at least very often

You could take a 4e character and actually play it in a 5e game, and it would work. The only thing you'd have to do is remove the half-level number increases. Other than that, it would work pretty much exactly the same as a 5e character. 4e characters are more complex in that they are heavily tied to the battlement due to movement powers. But, other than that, you'd be pretty close.