The clutter problem is unique to large-bodied animals in forests, such as primates. Smaller animals, such as squirrels, suffer less clutter because their heads are small enough to see in between branches and leaves. And large animals in non-forest environments can do just fine with eyes that face sideways.
So the reason we all have peepers on the front of our heads is by no means settled. Each hypothesis has its own strengths and weaknesses. But whether our eyes moved forward to account for leaping through branches, chasing after tasty bugs, or to see through leaves, at least one thing is certain: it all comes down to life in the trees.