Basically, trying to satisfy all aspects of a disparate fanbase is a fruitless endeavor. Each category of fan appreciates a different subset or edition of the game.
Some of these are incompatible due to exponentially rising overheads, especially balance issues.
Look at for example, multiclassing, if you have multiclassing, you have to either pay in variety(4E style, limiting what you can gain from multiclassing), balance(combining classes designed for different roles and expecting to get consistent results is a pipe dream even if not for differring gains at different levels) or originality(abolishing classes altogether, allowing for free pick of abilities). Multiclassing MUST either cap the returns, deny synergy or ignore balance concerns to some extent.
Some of these are mutually incompatible.
Elegance and brevity of game rules cannot be attained while satisfying semi-realistic game world. Rules for edge cases and varied environments take up space and add complexity. At the same time they are dealing with legacy effects, which cause an uproar if outright removed.
What I think they should have tried is to sell vision. 4E did that, except the attacks on older editions split the fanbase. It achieved it's own success, if not quite of the same quality. The designers should have a dream, and then make people believe it, and become invested in it. Instead they're going for centrist pandering in a divided environment. 5E does not appear to have a cohesive self image. It is defined, and trapped by the past, rather than carving a future in d20.
