Multi monitor support - a lot more people are using computers with more than 1 monitor (I'm using 2) It would be nice to be able to watch the match on 1 monitor without having any of the boxes on, but on my 2nd monitor be able to choose various sections of information that I want to see (a bit like on the home screen)
Offside replays - I normally watch the games with key highlights selected, and with the replays set to show goals. There isn't an option to show the replay of the offside that led to a goal not being given. It would be nice to have an option that could be selected or not to show the offside and it perhaps have a line shown across the pitch to give you an idea as to whether it was the correct decision or not. This would give you a better idea of what to respond when asked questions by the media after the game.
Pre-season tours - I'm sure in an earlier version of the game (possibly FM13 or FM14) you had to name a squad of players to take with you on a tour. It would make sense that you would name a squad of say 30 players to take, probably a mixture of first team, squad players and promising young players and then only be able to use those rather than being able to select anyone at your club despite you playing in America, Australia or Japan etc. It would also be nice for these tours to have both a financial cost, and a potential financial gain shown too before you create the tour so you could see whether it would be worthwhile you going.