This is ok. He's a leadoff hitter, and also probably the best pure contact hitter on the team. This is not a spot where power is a necessity.
Happ's relative lack of power is more problematic than Hoerner's. He is fine as a Left Fielder, but isn't the ideal middle-of-the-lineup hitter. I wasn't big on making a long term commitment to Happ, but the length and amount of his extension was reasonable, so I think he is a piece that the Cubs can work around.
It appears this is something we are just going to have to live with, but hopefully some more power comes along with those hot streaks. Swanson's OPS is being propped up by a very high OBP, but that isn't sustainable.
This, to me, is where the biggest problem lies. The Cubs made a big commitment to Suzuki as their starting Right Fielder and so far he hasn't shown himself to be the power threat that they need. The emergence of Bellinger has taken some of the pressure off, but Suzuki has still been a big hole in the middle of the order for most of the season. If that doesn't change, the offense will continue to struggle and the lack of power will continue to be an issue.