- All portals to the other earth were closed. Zoom is fatally sick. In a few years he would die by himself. No real reason to open portal to other earth.
- Barry is faster than Zoom. Barry captures Zoom but does not knock him out or anything. Instead Barry just talks to Zoom and fails to keep him captured. Also the trap they made for Zoom is stupid. Barry already is faster than Zoom so there was no need for a trap.
- When Zoom handed over Wally to the Flash team, why didn't Barry just break the deal and kill him or at least knock him out and capture him?. Instead Barry makes the most retarded decision he has ever made. He gives his powers to the serial killer Zoom, who could kill everyone in the earth especially when there is no one to stop him (the Flash is the only one who could stop him).
So Barry risks both earths for no good reason. Was he afraid to fight Zoom? Who knows. I hope they don't make this kind of writing mistakes in the future or the Flash is over for me.