It's a must, that much GLOOOOP here that without it your at risk of not driving home.
Evolution put your nose and mouth a foot above your lungs...why spoil a good design?
come on, 90% of the vehicles with snorkels probably don't get their axles wet let alone their air boxes, I agree for the few that do get into situations where they are needed then its a useful bit of kit, but most are fitted just cos they make some bland rover LOOK like it could go off road