I have a suspicion: People get the 18-55 (any version except WR) essentially FREE with the camera body. People shoot pictures (learning), read fora, become dissatisified with shoddy 'kit' lens (even though it's designed by Schneider, high-end lensmaker). People spend bookoo $$$ for chic 16-50, shoot pictures, declare themselves satisfied with new wonder-lens.
But... are they tricking themselves, getting psyched-out? Do they value the 16-50 more because they PAID so much more? Do they NEED to feel they've gotten their money's worth? "Well, my FA50/1.4 MUST be better than that old Zuiko OM 50/1.4, because I paid ten times as much." (I just missed an OM50 on the bay today -- it sold for US$20 + shipping.)
Galleries here are filled with splend images shot with the DA18-55. Pro work can be and is done with it, same as with a Holga. Blame not the tools.
"That's not the electric light, my friend
But your VISION that is dim." --L.Cohen