I still think that hitting Prestige Master in BO2 is a worthy accomplishment. For a somewhat above average player who mostly plays TDM (like me), it still takes in the neighborhood of 20 real world hours to get through a prestige. Meaning that hitting Master Prestige is an investment of ~250 hours. Not that I've checked, but you could probably finish every quest and unlock every achievement in Skyrim with that sort of time. How much more can you ask of a video game?
I play HCTDM 99% of the time and I had MP in either 7-8 days played. It is NOT hard to do once you start leveling all your perks, attachements, weapons, and challenges.
I finished ALL the achievements and 95% of the quests in 9 days on Skyrim. I think I had about 70 hours total on that first playthrough. After power leveling with the potion enchanting, Ohgma Infinium glitch (you needed to be level 16 to start it) and was at level 81 in about 4-5 hours I ran a few more times with different builds.