I'll just say this - the difficulty of Coil 5 (even pre-Echo) has always paled in comparison to the difficulty of finding a competent / available group to make attempts with, for anyone excepting hardcore gamers. Got a job or a family? Good luck working your schedule around 8 other people. If you're in school it's a bit easier, but it's still not a trivial task.

That is horrible, horrible game design, no matter how you slice it. The primary difficulty in an MMO in the year 2014 should always come from the fight itself - not from gathering people to do said fight. The group size for these encounters (8) is both too big and too small; it's big enough that maintaining / forming a party is difficult and unpleasant, and small enough that individual mistakes still trainwreck the entire group. SE absolutely needs to learn from this with the expansion, or they're going to continue fielding these types of complaints from a significant portion of their player base. Their current approach is also largely responsible for the toxic DF environment, because the small group size (but crucial individual roles) means people are very likely to leave quickly and/or begin harassing each other the instant someone screws up. Terrible approach on SE's part - they should be embarrassed.

In regards to the OP's suggestion specifically - moving to 16 people would be an option to minimize the importance of everyone doing their job, but I'd rather see a move to party sizes of 4-6. That's a lot easier for people with actual lives to set up schedules around.