It's more that BC and IC2 are the "OG" mods of modded MC. TE, Ender IO, etc. all benefit from seeing how successful a mod is when it includes ore doubling, logistics, upgrading, energy production, and to a lesser extent - armour/tools.
Though, I've only played since 1.4.7. Back in those days, BC was the bread and butter logistics next to RP2. IC2 was more prevalent than TE (TE was just getting big).
I don't think he meant addon, as in they were built to complement each other, more so that IC2 didn't include logistics, simply because BC existed and wanted to focus on other things, such as solar/wind/water/lava/biofuel/nuclear power generation, GT antics, etc.
Now mods are all about popularity, trying to monopolize on a players focus. That might be the key difference.
Edit: Whoops, didn't mean to repost.