Apple needs a few things to make their WM competitive out of the box: 4/6 corner tiling would probably be a good place to start: split-screen is useless. Hopefully they would have an auto-tile functionality like Yabai, Pop Shell or i3-gaps, since I've come to expect that on my high-res devices too. They should also copy Microsoft's FancyZones, which let you quickly draft window presets to keep your screen divided the way you like it. Any of these would be welcome additions, because currently it feels like my Retina display is being put to waste with only two or three apps all fighting for attention.
Not working how you prefer it doesn't make something unusable or broken...
BTW your supposed Mac mini has serious hardware problems, get that thing RMA'd ASAP! And man, why did you not RMA your MacBook Pro you bought a few years ago?? It was also just as broke!