i can understand people that only have 1 body having an issue and wildlife people typically will like to shoot landscapes as well as wildlife because of their interest in nature
and as I pointed out the tokina 11-16 works on current APS-H cameras without vignetting from 13mm to 16mm
13 mm = 16.9mm so pretty much has that covered
so there is an option
of course there is also the 14mm L and a few other options around in the primes
and rare i mention the 8-15mm
I currently use two APS-C cameras ( 7D and a 40D as backup), i shoot sports, portraits, wildlife nature , commercial product and people pictures. is not necessary to use a different body for a specific task (if you are on a budget), instead i use a different EF
lens for specific tasks, like 100mm macro for some prtraits and product photos, 17-40 for landscapes and other wide angle photos 70-200 for sports and other zoom situation, and a 50mm for portraits and people. all my lenses cost around $2000 under the price of a APS-H sensor body (including the new 7D2 if the rumor is accurate). I can cover all my photographing situations.
PS. all my lenses can be used on APS-H, APS-C and FF cameras . Who knows At what type of body i will upgrade in the future.