2E tried to change the sensibilities of D&D without changing the mechanics. 3E tried really hard to keep earlier sensibilities (especially late 1E, early 2E), but with cleaned up mechanics. In the process of trying to preserve
all those sensibilities, it ended up with a lot of mechanics. 4E, in contrast, tried to recreate some of the earlier sensibilities that were neglected by 2E/3E and streamline the mechanics for that, while cutting out things that didn't work very well. In the process, it neglected some of those 2E/3E sensibilities.
I get that the "how easy is the character to convert?" test makes 4E look like the odd kid out. I counter with, "how easy is it to replicate the feel of BECMI/RC play?" test and find 4E the best options with steamlined rules. (Not the best possible option, but of the printed ones, including clones, yes.) And for every person saying that it doesn't play the way they played Basic, there is one of us saying that the way we convert characters (by main sense of the character, not specific abilities) works pretty darn well in 4E. So around and around we go.
So this is part of why I keep saying that 5E could do a lot worse than to start with BECMI/RC, modernize the mechanics, go after the main sensibilities of play supported by those editions, and then provide
supplements to support the rest. They must be supplements, because the core game must stand alone.
To get that, here are what I think of as the critical tests, which are neutral on 2E/3E/4E sensibilities:
- Character sheet on one page, and not cluttered. Can't pass that test, then something got included for a more narrow target, and it doesn't belong.
- Can play a full game with just the material in one book (e.g. like RC) but easily and quickly supplemented by a compatible monster book, magic item books, setting material, etc. -- if you want to.
- About 6 races, about 8 classes, and you make characters that fight, explore, talk, and generally express themselves "heroically" in dungeons, woodland glades, mountain peaks, swamps, pocket dimensions, etc.
- You find some pretty basic treasure, some niftier things, and a few oddball things, too.
That's it. There are whole tons of things that belong in one of those supplements that are nice to have. Powers, feats, skills, prestige classes, extra classes, more races, "storyteller" elements such as background information, terrain rules, etc. It is possible that the barest bones of skills, feats, and/or powers might fit into that main, core ruleset, at least as options. After all, even RC had some guidelines on castles, and optional weapon rules. And certainly there is no requirement to keep "elf" as a class, or arbitrary level limits, etc. If some of the supplemental material takes supplemental pages on the character sheet, alright.
The only thing really wrong with this approach is that if you do a good enough job, you might sell a bunch of copies of that one book and then find it difficult to sell those customers anything else. But somehow I can't help but think that there is a market for power and feat supplements, class supplements, etc. for a core system as hot as all that. You might find "4E" folks buying mainly power supplements and "3E" folks buying mainly "character rounding out" supplements. But that's alright, if the core is good.