They do update gameplay until late in the year, considering... The questions is never an issue of will, but rather resources... I've talked to EA devs face-to-face. I know they are passionate about producing the best game they can, given the time and manpower constraints. I also know that the dev teams themselves aren't the only stakeholders in the process.
To fill in guys that don't know, every year the game drops and part of the dev teams starts working on the next year's game. By February or March, they have the core changes for the next edition locked in and ready to show to some Madden influencers. When I was more active in the community, they would invite about 15-20 Madden community members at a time to check out the game...
When I was last there in 2012, I made presented two issues that I didn't know were linked, but needed to be fixed, because they directly effected whether the rules of possession in the NFL were respected in the game. I was told, point blank, that they wouldn't be able to get it into Madden 13. I don't think it got addressed until Madden 15.
To give some background:
Once upon a time, a defender that jumped to catch an interception was awarded possession while still in the air. a Linebacker, for instance, would leap in the air, the ball would touch his hands and the screen would rotate. After the screen rotated, the linebacker would get both feet down and return the pick.
Unbeknownst to me at the time, there was also an issue where a defender at the sideline would ALWAYS drop interceptions whenever his feet were going to land out of bounds. Offensive players could catch a ball and land out of bounds, but defensive players dropped 100% of those passes...
Turned out, the game forced the drop at the sideline out of respect for the "screen rotation" that marked the change of possession. a DB that wouldn't gain possession always dropped the ball to account for the fact that a ball caught in the field of play was awarded possession too early.
It took two years to get it right... But they got it right. I still remember the first interception I threw where the linebacker got both feet down before the screen rotates. I've never been happier to throw a pick. 😆
All that said, the team likes to focus on a few key items that have longevity. The game ain't perfect, we have more control of all 11 players on our team than ever before. I find it hard to go back a year, once I pass my 100 game threshold for passing judgement.