A hot fix for how we receive for coins is needed. Yes, Niantic created this new system to combat stagnant gyms and for that goal, it works. However, a middle ground change would be 1 coin the instant a Pokemon is placed in a gym with a 1-hour cooldown. That way, win-trading is prevented and we all get a reward for taking down a gym. As for having multiple pokemon in gyms, the cap 100 coin daily (21 hour?) cap might have to be extended to a 700 coin weekly cap. Imagine taking hours out of the days to feed Pokemon in gyms only to have them all return on the same day with a reward of only 100 coins.
Coins have been changed since this post