SE, MCH and RDM have no Dots!

[Shurrikhan]

Also, granting everyone a DoT does nothing but make the game more homogenized than it currently is.

A shared addition of a core concept doesn't make anything more homogeneous than a shared lack thereof. The way its inclusion in the opportunity costs of one's rotation, with-DoTs from without-DoTs, however, can diversify rotations depending on the preexistant intervals and internal balance involved. DoTs themselves are a simple option check of "can I get x duration out of this as to make it worthwhile?" Free DoTs, further, ask the question of "is this global worth spending on this DoT given my current buff window, the GCDs required to execute a full combo, and the resources or effects generated thereby?" It's a shallow increase to complexity, but it's still something. I don't think any game's ever treated that as the exclusive basis for a class, though. You don't make a class based on the inclusion of periodic damage. It's not going to be a core aspect until there's a whole lot more involvement and synergy than simply "at intervals of 3 seconds over x duration".

The same is true of positionals. No one claimed Monk was based on positionals. It used to be based on attack rate and fine control of its combo 'cycles' available through open, stance-less skills (ToD and Fracture). Now?... Who can say?