First of all it is a good game and very addictive.
Anyway, here's my wish list.
1) Scouting new talent. It would be nice if you could visit gyms up and down the country to find the next Lewis or Tyson.
2) Negotiate tv/Box office deals
3) Negotiate merchandise deals for your boxer
4) Have more AI in the game. More promotors and have to negotiate with other promotors.
5) Be able to organise fights with your own stable. Eg I had 3 fighters in the heavyweight division in the top 3 ranks. I couldn't organise a fight without having to go to 4th in the world.
6) Have upturn and downturns in the industry. Eg at the moment heavyweight boxing is at it's lowest point in many years and very few people buy the ppvs anymore.
7) Have a league for promotors eg Don King is the number 1 promotor in the world. Frank Warren is around 3rd or 4th.
More interaction with your boxer, eg if boxer is injured, visit him and make sure he is ok. Or if the boxer underperforms in the ring, you can ask him what happened. If he had a great fight, you could praise him.
9)When Boxers retire, they shouldn't show up in the search list again and they should be forgotten about unless they publicly announce that they intend to return to boxing. There ratings should be down as they wouldn't have trained as much.
10) There are amatuers in real life, why not have scouts watching amatuers and if some one is impressing, try to sign him on pro terms. eg Audley Harrison or Amir Khan who signed for Frank Warren.
I think you have done a great job so far, you have a basis of a good game here but as every game, it isn't perfect.