Personally I think the lack of apparent "trumpets blaring" traction is that for once the "big" pack isn't just "Direwolf20's pack with a handful of additions/modifications". When it was just that, you only had a small handful of mods you had to learn and the rest if you were unfamiliar with them you could grasp over time by following Direwolf20's most recent series. His mod list also tends to be relatively static at its core and pivots around that core with some changes each season, some of which get incorporated into the core and some of which end up falling off for whatever reasons.
Running Monster, there's a heck of a lot more experimentation I'm doing as I try to do things with the unfamiliar mods in the pack, and there's a lot of those mods. And, for a ready example, RotaryCraft is a very seemingly complex mod with a lot of moving parts that isn't attractive to watch somebody do a YouTube LP or livestream with if they don't have it down at the expert level. Somebody who knows the mod like the back of their hand could probably do a pretty wicked series with it, but since it isn't so heavily used a lot of folks wanting to do streams and LPs are probably going to skip it. Reading the manual on screen is a boring activity, and then you have the portions where you have to engage in problem-solving without a safety net.
As an example, just pulling one mod from Monster and going with a (seemingly) simple RotaryCraft problem: I have a hydroelectric turbine I want to run. The simplest engineering issue is placing the thing and placing the water source yea blocks above it. But then you get to deal with the lubrication aspect and suddenly it isn't so simple. The math problem there starts with "how much lubrication do I need to supply at a steady rate to maintain functioning?". Then you have to ask how many grinders running in tandem does it take to keep that level of production. How many seeds need to be going into those grinders to keep pace. How many plants need to be planted to produce that amount of seeds on the mean? How many fans to run to handle harvesting/planting (and in fact, knowing I need to use fans for this instead of trying to run a traditional harvester)? How about the power for those fans? What about using sprinklers? Oh, I need to make sure to pump water such that there's pressure so the sprinklers run?
It's a lot of stuff that needs empirical testing. I'm sure somebody's done it all and there are people on this forum that I know love the heck out of that stuff, but it isn't plastered all over for a "general rule of thumb". And trying all that out on the fly is daunting to do on video. So nobody's producing that content, nobody's consuming that content, and that content just really isn't all that existent yet. Folks like Direwolf20 himself actually would either do the empirical testing in creative themselves or ask the mod authors for a cheat sheet and then give you the cheat sheet numbers, and suddenly it's a lot less daunting and you can do it yourself on camera and the knowledge can spread. But until that happens, it's much easier to go "screw that, BANK OF MAGMATICS WITH AN ENDERTHERMIC PUMP TIME!". Which doesn't really showcase or require running Monster to mess with, begging the question: why download a mod pack with a ton of new mods you aren't even going to learn/use yet?
(I also happen to personally find RotaryCraft daunting because there's a lack of progression gates for a lot of it. People in the know should be shaking their heads and wondering what the hell I'm doing messing with hydroelectric when I haven't even going through a lot of the other engines made. But that's a "me" problem.)
I like the inclusion of a lot of stuff I haven't used before. I'm just taking a while figuring it out, and I personally am admittedly having a hard time easily finding answers for things I know people have done the math for. Which leads me to defer messing with things until I have a lot of time.
Also, Monster isn't really officially into its "stable" release yet. That could have some impact as well. =)
