Face the reality KA. The E-class was conceived at a time when MB's resources were likely at their most stretched. They delivered a very conservative product that did not move the game on sufficiently. Sure it's build quality and reliability are beyond reproach now, but they have given up much ground in terms of comfort, refinement and general luxury.
Furthermore, they are simply not attracting enough younger buyers because the car is extremely conservative without the AMG sports pack. Even with it, it still looks like a product more suited to an older buyer, particularly when sat alongside the A6. As such they can't simply rest on their laurels for another 4 years for the sake of keeping happy a select few customers who only want to see evolutionary changes.
Expect to see major revisions with every facelifted benz, until they return to where they should be in terms of product competitiveness and market share. The newly released ML, A-class etc. will not be exceptions.
Problem is, these same words were said when the W210 was released, the W211, and I distinctly remember, the W212. People always allow M-B to have previously "flubbed" in the name of "having to change things around drastically to attract younger buyers". They've been pushing for younger buyers forever now. I remember when I had a W211 and was upset at how insanely different the W212 was, i.e breaking M-B's luxury-car-esque "evolution idiom", and W212 fans were telling me "M-B had to change the E look drastically to attract younger buyers", now they're saying the W212 is too much for "older buyers". I can almost promise that in 3 years from now, when the W213 rolls around, people will be saying the W212 facelift went for "older buyers" as well. and the "W213 is so drastically 'changed' because it has to attract younger buyers", and the cycle will likely continue.
Audi is changing cars so negligibly you can barely tell a difference between new and old, yet they have the young market on lockdown, BMW is actually making cars MORE conservative and carefully evolved, and are continuing to steal younger buyers within each segment. Porsche? The hottest car to youth is a 911 and it's looked the same for half a century. People love when designs become iconic due to evolved and improved execution. M-B has lost that plot, IMO. They already bastardized the CLS's original clean-elegance, they released an SL that is so seemingly not-hot in enthusiast-land you can almost forget the icon has been replaced after 10 years, the E-Class is going through extensive changes prematurely compared to before, etc. The S hopefully won't fall victim to this.
IMO, this is all just excuses by M-B for products that aren't up to competitive spec by M-B, which is why you can get E350's for over 20% discounts in the U.S with no sweat.
I'm sure the W213 will be a nice technical improvement, but the F10 facelift will pull further away from it, as will the facelift A6. Until M-B can confidently get back into their groove and do things on their own terms, without making it look so obvious that marketing is designing their cars and strategies, they'll keep losing share in the upper segments.