Yeah, I noticed the exact same thing and although I do like shallow depth of field, many of the close ups in Interstellar were just too shallow and distracting to the point of making me think: "Hey, almost nothing is in focus here, this must've been an IMAX shot."

Note that those shots with distractingly shallow depth of field were most likely IMAX, not 65mm. Keep in mind that the IMAX frame dimensions are:
Diagonal—87.91 mm Width—70.41mm Height—52.63 mm

While a 65 mm frame is:
Diagonal—57.30 mm Width—52.48 mm Height—23.01

It is for that reason I do not believe IMAX is good for close ups.

Sorry buddy, that's not true. ProRes is resolution agnostic, it can be anything between SD-5K and Blackmagic already has an agreement to record to ProRes, so anything the camera can capture it can output as ProRes.

Dude you sound like a PR guy for Nikon lol! But I have the D750 too and do have to agree with ya.