Players have supposedly been asking for it for a long time. And, now that the tech is largely in place, it provides what should be a much simpler/easier collectable item for them to plunk into various forms of content than creating an endless stream of new minions and mounts. Just create a new appropriate skin for the umbrella top and maybe tweak the handle a little and, boom, new thing to drive engagement in content.

I can understand not wanting it personally, or just not being completely happy with the current implementation (which may improve given time, just as "old" emotes are being added to sitting/mounted use now), but it's pretty easy to see why they added the feature.