I've found one of the bigger stumbling blocks to the uptake of anything above 1080p30 is hardware/software limitation, not the camera but rather the end users computer, so many people don't have capable enough computers to deal with higher resolution/bitrate files, playback and editing software is also quite limited still
Yea, I have a reasonable machine, can easily edit 1080p video...4k really chokes it...I usually crop the 4k or resize it before I edit it. (4k timelapse through DSLR or GoPro). So 1080 is just fine...but if you want auto stabilizers or digital zoom, you need to start with 4k and crop from there. However the output to the card should be 1080.