I never specified paid Plant Pass, just the Plant Pass overall. I too am a f2p player atm, and cosmetics are not really necessary, so I see them as a more premium feature, which leads to a likelihood of monetisation.
Costumes in the Dailys section of the Shop also work. There has been lawn decor for Gems in the shop before.
If the Zen Garden got a huge rework, it could be cool to see other player's collection of plants and the costumes they got on their plants.
I completely agree with your idea about the Zen Garden! Being able to visit other players' gardens and check out their customized plants and unique costumes would be amazing. It adds a great social element without hurting the core tower defense gameplay. Let's hope PopCap is reading this!
