IMO unless you live somewhere that it snows considerably more often that once or twice a year or, conversely, in the desert, fat bikes are an affectation and @plxarc will either enjoy that affectation and find little use for the 29er wheels or won't and will find little use for the fat wheels.
The weather and terrain to be ridden are unlikely to make the bike unrideable or even less enjoyable whichever set of wheels are fitted.
Nothing necessitates a fat bike. After all, you always have the option of walking. There are more things than drifts and dunes which can benefit from low ground pressure, like spongy moor tops.
Are you saying that snow necessitates a fat bike?
IMO unless you live somewhere that it snows considerably more often that once or twice a year or, conversely, in the desert, fat bikes are an affectation and @plxarc will either enjoy that affectation and find little use for the 29er wheels or won't and will find little use for the fat wheels.
The weather and terrain to be ridden are unlikely to make the bike unrideable or even less enjoyable whichever set of wheels are fitted.