I actually cringed at reading "Liam doesn't add that much to the group vocally."
Have y'all not seen Zayn look at Liam for help for musical keys. And Liam's voice isn't the greatest but his vocals do get shunned in the group. He has to carry the responsibility of making their harmonies sound well.
I've said this before. He's the one with the most vocal experience and most capabilities. His falsetto >>>>>
I fully acknowledged that he's a great singer, probably the best in the group. But (just in my opinion, obviously... I even said in my post it was subjective ) he could easily be replaced by any other talented male vocalist and their songs wouldn't sound that different
) he could easily be replaced by any other talented male vocalist and their songs wouldn't sound that different 
well...