This is a community forum and not a line of communication with EE, as such there won't be "anyone from EE" to give you a detailed breakdown on a commercial decision. We are all fellow customers on this forum, with the exception of a small community support and moderation team.
Ultimately the simple reason is that they just don't want to offer 12 Month minimum terms any longer. There will likely be no further public-facing detail than that.
Instead customers can just take a 1 month rolling contract and stay on it for as long as they wish.
