Keep in mind that while such cosmetic DLCs are very common in the industry these days, they are fairly new for Anno (we had something similar for Anno 2070, yes). The Holiday Pack and the pack from this vote are also tests for us to see what kind of content formats our community likes to keep the game exciting and fresh between the bigger DLCs which take a lot of development time. At the same time, we don't want to release new content just for the sake of it if we don't feel that players will enjoy it, and that it will enhance their experience.
So we decided that we pick three topics that we think are interesting (and that many people in the community asked for), and give the players the choice which of these packs they want to see. Does it mean that we will never use the other options? No. It means that for now we will do our best to create some awesome ornaments based on the winning topic, and if we see that players love this way of receiving additional content, we may revisit the other themes in the future. Please note I said "we may"- there is no plan for now, and no promise from me that it will happen.