http://m.ign.com/articles/2017/03/10/niantic-admits-pokemon-gos-gyms-have-to-change

Speaking to Polygon at the Game Developers Conference 2017, senior product manager Tatsuo Nomura said the following:
“The gym portion [of Pokémon Go] needs a lot more work, and we are trying to improve it and make a bigger change to how the system works,” says Nomura. “Overall, I think we need a little bit more time to think through how we do it.”

“We needed to define [gyms] in a way that works in a mobile game. For example, we didn’t have ... there’s no non-playable characters. That’s not how the game works. We’re an MMO, and we expect people to play with other people.”

Nomura goes on to note Niantic expected more people would get involved with the Gym portion of the game that there are currently, but concedes the system in general needs “refinement.”