I got use to working with the Finder in Cover Flow exclusively as I do a lot of Folder/file management between computers - Gallery View is cool for picture and PDF collections but little else IMHO. However, the List View comes with a side preview panel just like Gallery View so perhaps this is my 'go to' file manager screen (vertical instead of horizontal preview) - a 'poor mans' Cover Flow alternative.
I kind of agree – I like the new Gallery View, but I wish they would have added it
in addition to CoverFlow instead of making it the replacement for it. In my opinion, Gallery View and CoverFlow View serve slightly different functions – CoverFlow is better for quickly
scrolling through large amounts of pictures or media and for casually browsing through them, whereas Gallery View puts the emphasis more on the
individual file you have selected and doesn't allow you to scroll that nicely between many files. Scolling in Gallery View only scrolls through the tiny bottom bar instead of shuffling through the actual selected file like CoverFlow did.
It's not a big loss, and I know most people weren't really using CoverFlow anyway, but I found it nice that it stuck around till High Sierra and I don't think it needed to be dropped entirely. Those who don't see any use in it can just not use it; I don't think it would have required much development effort to keep it around for the few people who do find it useful or nice-to-have. But apart from that I'm really happy with the new Finder additions in Mojave, including Gallery View.