The reason is the new infrastructure up there: On some stretches the trekkers share their routes with cars and motorbikes.
Luckily the tourism industry has taken note of these complaints. In today's Himalayan Times there is a report on new trails being planned, the so-called 'disturbance-free trails' will open soon.
Now my only hope is that the Annapurna Area Conservation Project (ACAP) applies the disturbance-free-concept widely.
Not only cars and motorbikes are a pain in the ass for any trekker. Litter along a trail is as much of a nuisance: Empty chips bags, bottles and small black plastic bags (filled with stuff you don't want to know about) sure doesn't get you into that relaxed Himalayan mood.
Luckily 'eco-tourism' seem to be the latest buzz word in Annapurna.