I'm not a judo guy, I'm a bjj guy with a prior wrestling background.
My point on popularity is that it's not necessarily going to increase in popularity just by being in the Olympics. It won't be publicized, and it will air at obscure hours. Honestly, I think the global spread of MMA is by var a better vehicle to popularize BJJ around the world.
Whether the rule changes are random or not, I think they are bad. I think they weaken the art. As far as changes in judo, there used to be a lot more time allowed for ground grappling, you used to be able to do things like shoulder locks, and you can't do anything like a triangle with pulling the head, or a guillotine choke. I think this has made many judoka neglect the ground grappling aspect. Ask anyone who trains judo and they will tell you that schools nowadays range from teaching 50/50 standup/ground (very few), to schools that teach very little ground work at all. They have also banned several grips that are acceptable in BJJ (for example you can't grab 2 hands on the same lapel, and you can't grab a leg for more than 5 seconds or something, and now they have almost completely banned leg attacks as takedowns).
I think one of BJJ's strengths is that it is very much a freestyle/hybrid grappling art. There is the positional progression that awards points, a few restrictions on submissions (more than I'd like), but beyond that you can basically use whatever works, which is something that I think is great, and could be lost if it becomes an Olympic sport. By getting into the Olympics, your sport becomes a slave to the IOC, and loses its freedom and independence. If the Committee doesn't like something, it's out. You have no say. I tossed out an example. Say the IOC thinks that groundwork is boring or unnecessary, like they seem to think with judo. Do they make it more like judo? Doesn't that make it pointless to have such a similar sport in the Olympics? Or say they decide that you can't pull the head with the triangle, which is what they decided in judo because supposedly that's too dangerous. Do you think that's a good thing?