This is just a half-baked thought, but, isn't Control (CC, stunning, sleeping, fearing, et cetera) just as class-defining a role as Tanking, Healing and DPSing?
Under that logic, Rogues and, to a lesser extend, Mages, aren't pure DPS classes. The rogue in particular is a Control class. I could probably wax poetic on this for a long time but I'm not interested in a lot of "tldr" and annoying "COOL STORY BRO" .jpegs, so I'll keep it brief.
Conclusion: Do you think Control and Debuffing is undervalued as a class role? Do you think it deserves equal consideration with healing, tanking, and DPS? Why/why not?