So, now, instead of asking for pure support roles, you're suggesting that Square create a new hybrid/DPS role that can either do full damage or boost the party's damage. In other words, you've gone full circle and are, in essence, asking that the bard's buff spells be stronger.
However, let's put this to the test. You create this Bard+ class and it registers as DPS. This means for the duty finder, the class is irrelevant. If a party gets one and the person decides to play his support role, that means everyone else will be doing more damage, so the run will go a little faster. Otherwise, it has no bearing on the game. This means that for leveling and some early endgame gearing purposes, the class isn't needed, since the designers cannot guarantee the class is present. In more organized raids, should the class's support spells actually be more beneficial, any good raiding FC will require that person play in support mode. So this means the class's abilities will only be useful in raiding. This is close to what the bard is.
Or the designers could go out, and add the support role in. Now, everyone's duty finder queue times suddenly increase. It's now 1 tank, 1 healer, 2 damage, and 1 support for light, and 2 tanks, 2 healers, 4 dmg, and 1-2 support for full. This of course translates into raids, where the support role is now needed. You've gimped everyone else for the sole purpose of having a support class. Meanwhile, the more organized FC will investigate ways to optimize setups so that the support person can be supplanted with a better damage class, because hey, more damage means a faster clear. Sure, that means the support person would be playing 100% damage, which renders the support aspect useless.
I realize you don't like the trinity, but as I said, the tank/healer/damage role is the most basic group setup in a theme park raiding MMO you can get. Square's setup o spreading CC and support around the classes (like Blizzard has done) is most efficient design. It guarantees you can fire off a CD during a burn phase, but it also ensures you can complete an encounter without the CD.