The vision cone did do what it was built to do, and that's exactly what the problem with it was. It hindered the game's accessibility and usability, which resulted in a sizable portion of Madden's audience disliking it.
The vision cone was cumbersome to control (required the user to take his thumb off the face buttons, meaning a longer delay between when the user wanted to throw and the QB actually throwing the ball) and/or doubled the number of inputs required to make a simple throw (if the user used the "snap to receiver" button command). It was an ergonomic nightmare.
A user can already see a receiver breaking open with his own eyes; making sure his quarterback "sees" him too with an ugly flashlight overlay is an contrived inconvenience at best and an exercise in frustration at worst, particularly with a blitzing defense bearing down on the QB.
I readily understand what it was trying to do - create a concept of a QB's vision. It was effective at doing that, but at a usability cost, and a very high one at that, and Madden is already a hard enough game for new players to come to grips with without the vision cone. I would be thoroughly surprised if it is ever reintroduced into the game.
Sure, but not without a cost.
Every option added into or left in the game is another variable to account for when doing gameplay balancing / tuning or diagnosing online desync bugs. For example, the issue at the launch of Madden NFL 15 where some users playing head-to-head games in Connected Franchise were getting disconnected from each other on account of differing settings in their kicking HUD. Removing things outright which don't thematically fit with the current direction of the game allows for more developer attention for the things which the developer actually wants to focus on.
The developer sometimes has to pick and choose its battles with these things, and Tiburon obviously doesn't feel that the vision cone is the hill its wants to die on. Personally I think this is the best decision for the game; others may disagree and that's fine.