There is little to no apparent distinction in the basic passing mechanism, or results, for any Madden going back to at least 2003 and the advent of online play. The lack of route-based passing ensures that this won't change no matter how much we may desire it. The catching mechanics changed over time - rocket catches, jet-packs, aggressive catches are a few examples... The running mechanics changed over time - hit stick 1.0, hit stick 2.0, precision tackles... Defense has changed. Special Teams has fundamentally changed several times - to the stick and back now on buttons...
But the fundamental aspect of having 1 button mapped to 1 receiver and the QB throwing based mainly on the length of time the button is held down has barely changed...I know every few years we get passing modifiers, but in all honesty, they barely affect the overall mechanic...adding high, low and left right but then allowing the WRs to telepathically know which way to go, generating separation and catches that have absolutely nothing to do with the QB accuracy ratings, the WR route running ratings or anything else.
The QB is not only preternaturally accurate (regardless of player being an ovr 90 or an ovr 67) in head-to-head games - (and who is not familiar with the now annual lament of "robo-QB" with the AI?) - they also have the ability to guide receivers to open areas (the WR responds to the throw direction and adjusts in sync...whether physically possible or not!), where they magically morph open and cannot be stopped. This phenomena is far less prevalent than it used to be, but it's still there on seam routes, post routes and corners, just a little better hidden.
The out routes in 2016, the TE corner routes against man OR zone in some cases, the seam routes against almost any zone, especially C4, the cross field post routes, and on and on...the thing that makes these routes difficult in the NFL or even college is the QB has to be able to be more and more accurate and skilled to fit the ball into tighter and tighter windows....it was why Kurt Warner or Peyton Manning or Aaron Rodgers are/were fantastic and other QBs in the same offense might not have been close. In Madden, every year given enough time, every QB is able to make every throw, nearly identically.
Each year, the way to make this happen has been tweaked, but each year there is always one or two or three routes that give the QB-WR combination wonder-twin powers, regardless of ratings (especially in Draft Champions where Elite Elway was no better or worse than Stock Cutler or Mariota!!).
I agree with everyone who believe this will not change, and I also agree that the best solution would be to provide the option for people to change it in meaningful ways by their choices in the game settings. An actual "simulation" setting, where playcalling tendencies like constant streaks and roll outs would result in WRs barely able to move and OTs called for holding 75-85% of the time the QB rolls out and holds the ball more than 5 seconds....or where continual bump and run coverage results in more "illegal contact" penalties, etc. etc. etc.
That is one of my biggest beefs with Madden throughout the years - it's NOT the settings or even the results of those settings in stock games...it's the lack of acknowledgement that the head-2-head or online version of the gameplay is not even remotely "football" in its execution and flow. It could be, there are tons of great additions and material to work with over the last few years especially...it just is not going to happen. I have watched dozens of M17 videos and I can see the little changes in the way players move and control; but at a macro level I also know full well that the key passing gameplay mechanics are the same as ever - kinda like spam and powdered eggs, but a little Sriracha sauce added; instead of getting fresh eggs with Bearnaise sauce and a fine English Muffin.
Won't stop me from buying the game and finding like minded players to enjoy it with, but it will keep the game feeling very much familiar and boring eventually. I'm not complaining about the value of the game...hell I get literally a 1,000 - 1,500 hours or more entertainment across H2H, CFM, MUT, etc. - there is nothing else on the planet that is going to give me an entertainment cost of $0.04 - $0.06 per HOUR!! A standard 120-minute movie is like $7.50 per HOUR...so Madden is roughly the same as seeing 125 to 180, two-hour movies in a theater at $15 per viewing.
The value is there, the foundation is there, the opportunity is there....all that remains missing is the will to give the players total control over their experience.