The wormhole reopened because the current timeline is impossible.

They've already shown that the logic in this show states you can change the present by changing the past, Marty-McFly style. Eddie's suicide prevents Eobard Thawne from ever being born. This prevents him from going back in time and killing Barry's mother, which undoes all the events since that point. This means Eddie never needs to kill himself. Since everything then proceeds as it normally would have, Eobard Thawn is born over a century from now, and eventually returns to kill Barry's mom, setting in motion the events we just saw where Eddie eventually kills himself to prevent them.

There's a reason why history hasn't changed for anyone in the story - there is no valid timeline to which they can return. This is a major temporal paradox.