Because I always here that bigger wheels are better in the context of "rolling over stuff". This is why suspension was invented, to roll over stuff easier. On a hardtail, yes, I would definitely get a 27.5 or 29 (probably 29), but I'll never go back to hardtail so the point is moot. But on fs, it was a whole different ballgame. I felt that 29 handled like shit compared to 26, to the point that it outweighed any percievable benefit. As for 27.5, I did a lot of back to back testing before I bought my bike and I felt nothing, no difference between the 2. I understand that there is a benefit on paper, but it wasn't translating to 5.5-6" travel bike. Just saying don't automatically believe all the hype.
Funny how in the world of motox where rolling over things is also a big priority, no one is messing with wheel size.