Can’t they just admit it was a mistake? And errata it? Healing Spirit is broken out of combat, community spotted this 24 seconds after release. This “working as intended” attitude in the face of blatant brokeness irks me...
There are countless examples where the community saw something, screamed about it being broken, but when it was actually tested in real play, it was not a problem. The iconic example was the Mystic Theurge in the 3E era. When released, people screamed about how we'd never see another spellcasting PC that was not a Mystic Theurge and that the insane number of spells they had broke every facet of the game. It wasn't just a few loud voices either - it was many threads on many boards with many different people screaming about it... but 6 months later, nobody was playing the class and nobody believed it to be overpowered anymore.
Here, you have to be able to move through the spirit's space to use it (or start your turn in it). It requires concentration and heals a maximum of d6 to a creature per turn at 2nd level (there are tricks that allow multiple heals per round), and escalates in healing by using higher slots. It is only druid and ranger (or sneaky bard).
An enemy can occupy the spirit's space. Suddenly, the font of healing is gone until the druid or ranger moves it using a bonus action. Even then, moving the spirit into the space of an ally does not heal that ally - so you can't use it to heal allies on your turn. They have delayed healing that does not trigger until the creature's turn. If you are unconscious (which normally severs concentration) or unable to determine that the ally has entered the space of the spirit (can't see it, etc...), you can't heal them.
This is an effective healing spell whenever everything is working right, but it isn't going to work right all the time. In my opinion, it is totally fine. JC is taking a Superstar approach by watching and not jumping to conclusions.