This is the model in ALL of gaming, not just SI with FM.
The development cycle is such that the first version of the game is essentially a beta. The players test the game and in 4 months most things are fixed. But then the "improvements" made to the game for the next edition seem to break the game. Over the course of a few years, those improvements are really great improvements, but from year-to-year it can feel like regression.
For me personally, there are a few things about this game that are gigantic upgrades. I LOVE the new training schedules. Playing with sliders with essentially no clue how they worked underneath the hood was maddeningly dumb design. I'm glad they went away from it. I train my players almost exclusively using role training (focusing on a combination of a players best and worst roles in order to mould them into a well-rounded player as much as possible).
The transfer deadline day interface is immensely fun and informative and really has helped immerse me into the world of my save.
And lastly, I personally think the Director of Football and Head of Youth Development positions, along with increased ability to delegate, are great additions as well.
All of this is making me take less time to perform certain activities, and doing more of the parts of the game that i find fun; buying/selling young players, building the team from youth, and scouting. I'm not a tactician, I like being a team-builder, and the tools for this are much improved.