It's interesting, Zoe WAS a little immature, but I didn't think she was overly so; she IS a teenager, and she has a playful and flirty nature, which is still the same in the reboot.
Really I thought Yoon was far more immature than her, largely thanks to her very sheltered upbringing and married life - she flipflopped so damn much when it came to being in a relationship with Zoe, it was frustrating.
Which is why I'm enjoying their dynamic much more this time around even if I do miss some of the scenes the two had together in the first version, particularly the last one where Yoon gets spanked for not using her phone and letting Zoe know about changed plans. That "do you know how to properly use a phone? No. You. Do. NOT." while being relieved and exasperated rather than angry and seeking to hurt, was hilarious to me.