Hi Fail G.
A number of reasons for reduction:
1. Players lose ~ 20% value in addition to the star season on season, so it can make good economic sense.
2. Your best 14 anyway determine your Cup level & opponents.
3. At higher levels $ becomes increasingly important.
4. Also with 2 of my teams being ex 35T leagues, unfortunately there is less sentiment to hold on to players, as they are very competitive leagues.
My style is to have a 5*/6* balanced squad rather than 1 or 2 superstars. IMO some legends of the game have done that (1 x 7*/8*) in 35T leagues and failed spectacularly.
I generally get a minimum of 3 seasons out of players, up to 6 for young neg players. Although have not had a 300+ match player yet.