When it comes to the DPS classes, which all in their own way fill a fairly simple role; I hope each one brings some utility that compliments them with other similar classes and also potentially with different classes (ranged casters vs melee + tanks and priests).
Especially to allow a little extra utility for other classes to offset the current Enchanter which brings so much to the table.
Enchanter - Melee haste, casting haste, mana regeneration, enemy attack slow, enemy increase fizzle chance. Ontop of the main CC role.
I'd like to see buffs that the DPS classes can cast on others:
Monk - Melee haste (could stack with ENC) + STR buff (tanks, melee DPS)
Rogue - Poison or disease weapons procs + DEX buff (tanks, melee DPS)
Ranger - Nature based weapon procs + AGI buff (tanks, melee DPS) / spell hate reduction (priests and casters)
Wizard - Spell damage + INT buff (casters) / Elemental weapon proc (tanks, melee DPS)
Summoner - Spell haste + WIS buff (priests and casters) / damage shield ~ could stack with DRU? (tanks)
What utility would you like to see?
I'd like to see all classes have utility, actually, preferrably benefitting additional/other classes. It makes sense that a melee class would have utility to benefit melee, but might be interesting if it also benefitted casters. So, in your examples, the monks haste would also apply to spells. The rogue could give DEX for melee and +% to spell hit. Tanks could have +DEF or +AC for group members. Priest classes could give a bonus to avoidance or increased mitigation or regeneration. Utility, imo, encourages grouping and synergy, something I hope we see a lot of in Pantheon.
Why limit DPS classes taking from the Bard or the Enchanter (Control/Support). Start giving DPS classes Heals, maybe some Health buffs, a rez here and there, perhaps some tank focuses so your Rogue can play an avoidance tank.
While I see your point, there are distinct roles for a reason. If you wanted to water down one role, you should expect that for the other two chief roles (Tanks and Healers).