Every season, clubs lose players for the year because of preseason training mishaps, car accidents, drug busts, DUI, door punching, pissed-up brawls, trial games and even playing football.
Whilst I agree that each club has a core group of players with which it would be stupid to risk unnecessarily, the fact remains that these are professional athletes and playing and entertaining us fans is the sole reason they exist. To swing the pendulum so far to one side in an attempt to guarantee no injuries would only result in either madness (only play DCE for 5 min a game or finals only) or a team of pampered nancy girls scared of their own shadow.