Larger nozzles do kick ass. I personally use my 0.6 nozzles pretty heavily. As others have mentioned though, there are definitely scenarios where you'll really want or even need to drop to a smaller size. My printer hates trying to print PETG at higher sizes for example, maybe my hot end isn't powerful enough.
it also consumes way more filament- especially on single-wall parts or parts that have x perimeters rather than a perimeter thickness. They're great for structural prints, and large prints that you want done quickly. For comparison, a .4mm nozzle will have a nozzle area of about 0.125 mm^2, where a 0.6mm is .28 mm^2. and .8mm is .502mm^2. More than double the extrusion width.
like basically everything else in 3d printing, it's all about compromise and which compromises are acceptable.
I printed some tiny but detailed board game pieces recently, I don't think I'd get the detail I wanted with a 0.8. I also have Revo installed so I'm okay with swapping nozzles frequently.