I actually really enjoy five player dungeons. One of my disappointments in Mists of Pandaria was that we never got any five mans beyond the start of the expansion and that they basically became just a means to farm some valor - since no new fives were introduced, they couldn't be tuned to in any way keep up with gear from Throne of Thunder much less Siege of Orgrimmar. They became laughably easy unless you were running them as Challenge Modes, ultimately.
And this bothers me because I'm one of those people who feels like five player content never really had lived up to its promise in World of Warcraft. Especially now that raid dungeons have become so accessible, with LFR and flex making it easier than ever for almost all players to get some level of raiding if they want it, I've always felt like fives need a refocusing. Having normal and heroic difficulty fives really separate with better rewards for fives is a good start, but where Challenge Modes didn't grab me was in their completely cosmetic rewards. I always felt like CM's should offer gear on par with at least normal mode raiding - a group that decided to focus exclusively on Challenge Modes or some other form of very hard five player content should be able to progress their character not just visually, but actually as well.
Why do I feel this way? Well, I'll tell you.