I'd like to put in my two cents on this:
I think that most (particularly new) FTB players tend to go for the easiest system to set up that gets them the most reward with tech mods. While they have a great many mods to use to set things up, they generally only pick a few to use in their system. Look at MFR autofarms; they've become the standard way to automate tree and crop farming. Why? Because they're too easy. Put down dirt, put farm block, use EnderIO or Thermal Dynamics connected to farm and harvester, provide power and initial seeds/saplings, and you're done. The process is very simple, and very efficient. You even get sludge from the harvester that you can pump out for bonus stuff (very helpful in skyblock modpacks). Most players choose MFR over Forestry MultiFarms simply due to the easy setup and easy maintenance. RF is very simple and easy: Fuel -> Generator -> Conduit/Duct/Whatever -> Machines. This simplicity helps bring new players into the world of "heavily modded" Minecraft, introducing them to power mechanics that are now second-nature to FTB veterans like us. When I first started playing FTB in 1.4.2 (FTB Beta A), and I discovered the "Redstone Furnace" from Thermal Expansion, the first thing I thought when I built it was, "Where's the fuel slot?" and "What are all these tabs?" Then when I discovered it needed some sort of power, I looked for something to power it. I tried the windmill from IC2, with refined iron wires. For reasons that are obvious to me now, it didn't work. The very concept of multiple types of power (EU and MJ) were too much for a mod newb like myself. It took me about half an hour before I even realized that IC2 could not be used to power MJ machines. My point is, RF is user-friendly, and very intuitive. It doesn't require any understanding of how electricity works in real life, or a lot of research to discover it. Being newb-friendly makes RF (and MFR) so appealing and so successful.
Someone was asking about modern mods with "hardcore" energy storage and transfer. The only modern mod I can think of that has "hardcore" energy storage and transfer is GregTech. I did a little bit of a playthrough (before my computer crashed) of Beyond Reality, and even the first steam tier was intimidating. GregTech is a hardcore mod, and attracts players who are looking for a new challenge. Thermal Expansion, Thermal Dynamics, and most of MFR are excluded or disabled to force the player to go with GregTech, and try something new. I couldn't build an MFR tree farm, so I experimented and used Thaumcraft insted. It turns out golems are far more efficient with jungle trees, and better looking. You don't really play GregTech for the perks of fast ore processing and doubling. You play GregTech for the new challenge. These are players who don't want an easy route like RF; they want to do things the hard way.
I've found that playing FTB simply for setting up bare-bones systems to get exactly what you want as easily and efficiently as possible becomes very boring very fast. I used to play this way, with ores going into TE pulverizers and then into redstone furnaces, but that kind of setup gets boring really quickly. What I've found is that it's more fun to make your systems as interesting as possible, even if it means your resources take more time and use more energy or (gasp) fuel to reach their destination. Sure, you can have a cow farm with an MFR breeder and chronotyper, then pushing into a third pen with a grinder or butcher, but that's not as fun as that third pen putting cows in minecarts via Railcraft, which drops the cows onto a conveyor belt leading up to a small building, dropping them into BoP quicksand, where more conveyor belts move the drops into a hopper and into a chest minecart (more Railcraft), which gets all the drops to your chest/barrel/AE/whatever. Why use Railcraft and conveyor belts to do all that transport, when Itemducts and straight killing are more efficient? Because it's more fun. Look at ScottulusMaximus, rhn, epidemia78; their builds aren't just for the aesthetic feel, they make every piece of their bases an important part of the system. ScottulusMaximus' automated steel factory isn't just a couple of ducts hooked up to a blast furnace in his backyard, he routes coal coke and iron into a building with Railcraft, drops them onto MFR conveyor belts, routes them to another building with the actual blast furnace, creates the steel, melts it with TConstruct, transports the molten steel again via Railcraft, re-casts the ingot with a TConstruct casting table, routes the steel ingots back to where the coal coke and iron came in yet again via Railcraft, and only then is the steel put in the AE system. My point is, going just for the most efficient and compact build is only fun for so long. After that, the only way for tech to be fun again is to stop looking for the perfect system, and start creating the most interesting one.