Why not?
I mean, the debates around 4e revealed a few key issues/talking points for the "D&D community" (I use scare quotes because what exactly that is is one of those talking points).
When you discover that the connection between many of your customers and your product is not utilitarian but deeply sentimental in some fashion (such that eg matters of technical layout of game elements like spells, class features etc play a
fundamental role in market uptake, apparently at least as big as the details of the mechanics themselves), why wouldn't you run a market campaign that speaks to all that?
This I don't agree with - certainly not fully, at any rate.
Mechanically, 5e owes a great deal to 4e. The idea of "bounded accuracy" has its origins in 4e, which was the first version of D&D to be designed for a roughly constant hit-rate (the "sweet spot") across all levels of play. But 5e dials down the level bonus slightly (subject to magic item issues that [MENTION=12749]MwaO[/MENTION] has mentioned); and whereas 4e goes for a roughly constant 2/3 hit rate for both PCs and NPCs/monsters, 5e seems to step the PC hit rate up to 70%+ while stepping the NPC/monster hit rate down to 50%-ish.
5e pays a great deal of attention to detail with its damage expressions (evident in its use of non-traditional damage expressions for such classic spells as cause light wounds and fireball, and its departure from traditional level scaling as seen eg in magic missile and fireball). This is a direct legacy of 4e.
5e also has an intricate action economy, built on the 4e foundation; a system of long and short rests, like 4e; and an intricate (if controversial) encounter-building system that likewise builds on that earlier foundation. And connected to that encounter-building system is a system of "balance" around asymmetrical resource suites which clearly owes a lot to 4e (including Essentials) - in AD&D, for instance, there was no obvious design logic behind fighters getting a bonus attack at 7th level when MUs got their fireballs at 5th; whereas in 5e the 5th level extra attack and 5th level fireball are deliberately correlated as part of the overall logic of class design.
What's intersting to me is how close 5e hews to 4e design ideas, and yet how significant the points of departure are: in combat, there is the "bag of hp" monster design and the capacity for mostly-daily oriented PCs to nova; in non-combat there is the lack of a skill challenge-type system and the effect of non-scaling on skill checks (which I think [MENTION=12749]MwaO[/MENTION] also noted upthread); and perhaps most significantly, the asymmetrical class resource suitses, requiring the GM to manage the adventuring "day" to ensure balance, is a big obstacle to an encounter/scene-based approach to play, and favours a return to 2nd-ed style pre-authored and GM-managed scenarios.
Then there is the packaging - eg some people clearly place importance on writing out a spell description like this:
You create three glowing darts of magical force. Each dart hits a creature of your choice that you can see within range. A dart deals 1d4 + 1 force damage to its target. The darts all strike simultaneously, and you can direct them to hit one creature or several.
Rather than like this:
Target: One visible creature
Effect: The target takes 1d4+1 force damage, and you can repeat the attack twice, against the same target or a different one.
But that has nothing to do with mechanical design.