Reality check on aperture, DOF, and Telephoto lenses

So, over on the other forum there is complaint that the new 40-150 should be faster, say starting at f2.8 or something like that. Looking at the specs, the lens seems really small for what it is. At any rate, the complaint was associated with DOF and the slow aperture. For a telephoto lens, I would agree that we could all use more light, but shallower DOF?

Some numbers with subject 10 feet away:

150mm @ f5.6 gives me .22 feet of acceptable focus on :43:
25mm at @ f2.0 gives me 2.9 feet on :43:

150mm @ f2.8 gives me 1.32 inches on :43:.

APSC
200mm at f5.6 is .15 feet
FF at
300mm at f5.6 is less than an inch.

At less than an inch with a subject, like a bird, 10ft away, would be difficult to shoot, IMHO. Do we really need shallower DOF when using a telephoto lens?

 

Not saying it isn't, but I wouldn't consider the DOF decrease in the case of m4/3 an issue.

And I shoot birds at 10 - 15 ft away all the time with my 40-150. Someone in the apartment complex put up bird feeders last year.