What's with the sudden weather-sealing craze ?

Olympus 12-50 and 60 macro

Panasonic 12-35 and 35-100

thats four so far out of about native 25 lenses, not counting that 3d thing, that toy cap, nor any 3rd parties lenses from el cheapo to ludicrous..

Thats no craze, its only cool that we start to have that choice.