a note on permissions:
courtesy or not, mod authors are creating derivative works. It is only by the (extreme) courtesy of Mojang that they are even permitted to use adfly links to their mods, as most games that permit derivative works do NOT allow third party mod authors to accept payment for their work.
Frankly, the attitudes by mod authors that demand any more than a simple credit for their mod in a readme file are extremely destructive of the community, as are mod authors that demand extreme shows of genuflection, such as publicly posting conversations where permission was given (Covertjaguar) or demanding that no one create further derivative works (Eloraam), mod authors that essentially demand that people play the game THEIR WAY and no other way (Flowerchild) and, most especially, mod authors that explicitly include destructive code that specifically targets and sabotages modpack collectors (sirsengir).
I know that they feel their income stream or praise demands are being unmet, but as an indy developer I have only one sentence that I can pass to these people that would truly communicate how I feel about their particular predicament: If you don't like being part of the community, make your own damned game. I appreciate the work these people have done, and will tell them so repeatedly, since many thrive on praise, but not one of these individuals is paying a licensing fee to Mojang to be an 'official addon or dlc', and thus, their concerns about individuals using their modpacks on a single server are not only entirely groundless, but akin to the crying of children when they 'lend' a toy to daddy who doesn't play with it the right way.
Their 'copyrights' have absolutely no legal leg to stand on, as derivative products, even disregarding the 'fair use' policy included in most nation's copyright laws. If I create a new space ship out of legos, I have absolutely NO legal rights to prohibit others from using my 'spaceship design' or even taking pictures and distributing them.
Socially, it is polite to ask permission CONVENIENCE PERMITTING, but asking each and every server owner to get individual permission to use these mods is trivial and childish. and FTB's demands for such egregious displays of grovelling just to satisfy some deep seated moral masochism are irrelevant. I will happily continue using FTB for my single player games, due to it's easily-modified nature and a friendly user interface. (with a lot of mods removed and a ton more added that make the game much more fun than FTB's basic packs) but for my server, I refuse to leap through their moral outrage-inspired hoops of fire to distribute my server pack. I will distribute it through technic, who's understanding of the legal groundwork is much more approachable for the thousands of individuals that run servers and fuel Mojang's growth (Who DO have a legal and moral leg to stand on regarding their core file distribution), or I will ask my users to use a tool like MultiMC to create a direct modpack.
. Although if the Ultimate Pack would come out sometime in the next century, I probably would just use that and give a big middle finger to the mods not included and just live without them.