Nope, although I'll keep an open mind. 4K is an insane level of detail for viewing on a monitor or typical living room TV setup, so if I did want that format I'll just crop in post and be confident that no one is going to notice in practice. It's not like the lens (filter, really) is going to add resolution, so you could even use a combination of vertical crop and horizontal stretch to achieve the same aspect ratio and get a similar IQ - whatever works best for the given scene.
Also, most personal displays are still geared for 16:9 or there abouts, so unless you are shooting B-roll for cinema movies on the cheap with a Mavic, or maybe are looking to show off an ultra-wide desktop monitor, I'm not even seeing much point in it.