- He gets high-profile guests across a decently wide spectrum and at an overall high volume. >95% of his interviews don't interest me, but for the 5% that do - say, John Carmack - the name is the main draw. These people just don't get interviewed all that often so it's an event regardless of the MC. Probably the same for his entire audience, just different 5% slices.
- If you know the old mystery TV anthology show Columbo, he does a similar routine to the titular character: He plays the unassuming everyman and then asks unexpectedly smart/pointed questions, using simple terms but with reasonably deep implications. His interviews seem generally well-prepared. They don't go particularly deep on any subject matter, but if you're familiar with the subject matter they still prompt interesting responses from the guests - you can see someone like Carmack or Musk go into rubber-duck debugging mode trying to digest complicated thoughts into succinct answers and that has an interesting information side-channel to it (it tells you what they really think is important to say or highlight, and Rogan seems to be aware of this - he is good at getting the bits they personally find important).
- Related to the above, the macho/masculinity slant aside he acts humble and un-obnoxious. I might feel differently if I watched any episode with a guest I really dislike (because he seems to be more accommodating than challenging/critical, for sure), but in the episodes I watched I wasn't annoyed with him.
- Part of his prep is also clearly to read up on recent/controversial things related to a guest and probe for it during the interview, so there's the shock value/titilation factor that adds to the entertainment. His skill is that both him and the interviewee anticipate this but he still puts his subjects at ease enough in the moment to make the responses compelling. It has your brain constantly working to sort through what is guarded and what is not (=real), just like quality reality TV (everyone knows reality TV is scripted -- the entertainment is in trying to identify the sliver of authenticity in people's emergent behavior on camera).