While it is too soon to tell whether 5E's reception will be as positive as 3E's was, it does seem that it isn't burdened by a lot of the negativity that plagued 4E right from the beginning.
In some ways 4E's run was rather tragic - it didn't really get the chance it deserved. I think a lot of this is on WotC, but some of it is excessive nerdrage. I mean let's be honest, as a demographic we are VERY tough to please and VERY easy to offend (I'm guessing someone out there was displeased and offended by my saying this! But please note that I am saying "we").
You're really talking about a specific segment. There's a segment of the fanbase that enthusiastically adopts every new edition without question - they're the ones generating the most glowing, least critical positives, right now, just like they did early in the release of 4e and 3e.
There's a segment of the fanbase that gives each edition a fair chance and judges it on it's merits (I'm guessing, a pretty darn small segment).
There's a segment that views each new edition with suspicion, but eventually comes around.
There's a segment that cleaves off and sticks with the last edition, each time a new edition comes out.
And, yes, there's generally been a segment that might nerdrage at the slightest provocation.
I think 4E "failed"--by this I mean wasn't adequately embraced by the community and had a run that was too short and bumpy to be considered a true success--not because it wasn't a good game in its own right, but for three main factors:
1. PR disasters - the anti-3.5 rollout, the online tools debacle, and just general poor communication
2. Style and Presentation - including anything from non-traditional aesthetics and art to too much white space in the books, to feeling "Warcrafty" to many
3. Mechanics - focus on tactical combat, grindiness, AEDU paradigm, etc.
Not so much, really. Those were mostly things that edition warriors latched onto, but they were either nonsense or would require a much thinner skin than the fanbase has displayed before or since, and didn't contribute to the short run so much as create an opportunity for Paizo to clone 3.5 with Pathfinder. But you did catch a real issue in that list of edition-war-era talking points:
The failure of the on-lines tools was not just a PR embarrassment, but a fatal blow to the business model of D&D at the time - DDI was supposed to generate an unprecedented, MMO-like revenue stream that would push D&D to revenue levels not just many times what it had done before, but several times those of the whole TTRPG industry, in total. When it failed in development, the D&D line was essentially (pi) doomed. Fortunately, Hasbro changed policy and failure to achieve 'core brand' status didn't result in the line being shelved, just re-booted yet again. Now, happily, Hasbro considers all of WotC (stodgy, low-revenue D&D, and high-flying CCGs) one unit, and is delighted with it's overall performance, so 5e is assured a normal run, even if it were to deliver only a fraction of the revenue of past eds, or fail to so much as un-seat Pathfinder. Unless Hasbro has another change of leadership/philosophy, or CCGs suddenly tank.
So my view is that 5E simply doesn't have anything like these issues.
Here, we're in complete agreement. Mechanical improvements and innovations have been rolled back, and any new ones have been /very/ cautious and measured in implementation, and care has been taken not to ruffle the feathers of those who reacted so badly. More importantly, D&D no longer faces any meaningful business challenges. WotC can drop it a few resources to keep it going while basking in the glow of it's CCGs' successes. There's no fight for survival, no need to prove itself as a viable IP - basically a free ride at this point. Which is great...
Yet. I'm not saying stuff won't arise, but I think if there was a big problem we'd know by now.This doesn't mean there won't be a 5E equivalent to grindiness--which if I remember correctly, took a few months to really reveal itself--some aspect of the game that a large chunk of folks find tedious or boring.
Seems unlikely that specific problem will show up. The monsters I've seen in the pdfs, so far, have been only a little tougher - and a little more harder-hitting - relative to the lightning-fast playtest. 5e will likely prove a game heavily weighted towards roll-overs and TPKs, but artful DMs will be able to walk the tightrope in between. Worst case, as it succumbs to the inevitable power creep, it may turn into "rocket tag." The only danger of play really slowing down lies in the complex rules for casting, and comparatively vague rules in general. Rules arguments, if the DM isn't decisive and firm (to put it politely), could eat into session time far worse than grinding through a solo's last 100 hps. That and the usual suspects of playability outside 'sweet spot' levels, inaccessibility to new players, class & encounter imbalances, and so forth.
Really, the same mechanical and play problems D&D had over most of it's history - and never enough to stop it from succeeding on the basis of name-recognition and loyalty.