Perhaps the best reason for IPVM to go is because the show's is not as newsworthy as ISC.
Hear me out on this one.
I'm guessing that the majority of people on IPVM that would like coverage on ASIS 2015 are not attending. This could be for scheduling reasons/work-related reasons. But it could also be for the same reason you give: the lower density of truly valuable information. So if your only gonna go to one show a year, you are might make it to ISC, and skip ASIS.
But that's not to say it has NO value, just not enough to take another week off and get on a plane. And if it was in your home town, you show up for an afternoon right?
IPVM is the proxy thru which members can attend ASIS with limited cost and commitment. IPVM represents the combined desires of its members by attending. A single weary IPVM boot-on-the-ground does the walking for hundreds of members feet kicked back.
Also, for many members, a certain intangible benefit comes by having knowledge of even the most idiotic trade-show 'stunts', as the following hypothetical exchange shows:
Slick Salesguy: So these cameras are of course fully ONVIF compliant...
Big Buyer: Groovy, baby, groovy. <chuckles to self, then becomes self-conscious at the silence>, you know 'Austin Powers' at ISC?
Square Salesguy: You know I didn't actually make it this year; I think they are mostly irrelevant....
IPVM going to ASIS is a way for those not attending to get some feel of what it was actually like at the show.
In the same way that I'm wasn't motivated enough to go to the Jefferson riots personally, but more than eager to spend a couple nights watching CNN, IPVM can provide a little news to a lot of people.