The point is:
If you make them stances the idea becomes that you can swap them at any time with one push of a button, and the entire season system is designed for you to NOT be able to do that and it has to be intentional, or it wouldn't make sense.
Love it or not, on demand instant swapping between season is not what they wanted for the class, or the mantle spells would not have a shared 20 minutes CD.
Asking to make them stances is asking to fundamentally change the concept of the class, which is fine, feedback is feedback, but it's not just a minor tweak, especially when they basically just released the seasons system.
Druids are not supposed to swap their 20% bonus from damage to heals whenever they want, or they wouldn't have set it up this way.
You can still heal in Winter season, you'll just heal for less, the reverse applies to winter, with the middle seasons for mana regen. Is the system perfect, or even fluid? I don't think so. It definitely needs more work, but with instant swapping you would have a class that can optimally fill 2 roles in a group at the same time: dps and healer
That is not only the opposite of the seasonal system's design, that's basically the opposite of what they want the game to be.
You join a group as dps, you do damage. You join it as healer, you heal.
We can swap things around during a break or a party shuffle, but no one can swap roles in the middle of a fight like Druid would be able to do with Season stances.
They didn't even add a second hotbar to force you to make choices (and I for one think that we could really use a second hotbar), I don't see them turning one class major system from spells to stances just like that.