As a former main-healer in many other games, I'd like to weigh in on what I like about STO.... and what has caused some misunderstandings for folks with regard to "class roles" as they relate to the MMO Holy Trinity (tank, heal/support, dps).
This game still very much has these roles. They're just divided and used differently, with responsibility shifted. Below, I've listed the "Classic" role with STO's "Revised" role.
TANKING - Classic View: The tank is given abilities to generate and keep aggro, allowing him to make use of super high defense. This allows healers and DPSers to spam away, because the tank is responsible for holding the aggro. One person does the job of aggro management.
TANKING - STO Revised View: On the ground, the tank is given 1 ability and 1 trait to generate aggro. In space, the cruiser is given very high defense and more available weapons. In both areas, it is not the job of the tank to generate aggro while the other classes spam. Instead, other classes can use a variety of aggro-DUMPING abilities and careful target selection to avoid keeping aggro... and the tank's job is simply to make sure he keeps his name on each enemy's list. The overall job of the tank (to absorb damage) remains the same, but the group shares the task of aggro management.
HEALING - Classic View: The healer's job is to continuously heal the tank, while spot healing other group members as needed (AoE, accidental pull, etc). This keeps the tank free to spam aggro abilities, and DPSers free to spam damage, because the healer is watching health bars. One person does the job of health management, and the healer class has one job--healing.
HEALING - STO Revised View: The Science officer has a range of healing and cleansing abilities available... but also debuffs, buffs, exposes, and crowd control. The Science BO powers allow for some shield healing... but also debuffs, power drains, and crowd control. All ships have access to some of the healing skills, and all Officers have access to consumable heals. This leaves the 'healer' responsible for spot heals here and there, Heals-Over-Time and defensive buffs, and reducing out-of-combat downtime. Other than that, they are supporting through debuffs and crowd control--"healing" by preventing damage or by speeding up the fight. The dedicated "healer" is no more, as everyone shares the job of health management, freeing the officer up to switch between healing and support.
DPS - Classic View: DPSers jump in, get behind the enemy, and bash away while the tank holds aggro and the healer keeps his bar up. Aaaand that's it. Wait for the 10% mark, burn your cooldowns, and brag about your DPS meter.
DPS - STO Revised View:In space - Carefully select a target. Jump in. Smash. Jump out. Jump in. Smash. Jump out. If you collect an extra, shake him off on the cruiser. Strafing runs, rather than park and spam... or peel one target at a time off the cruiser and burn them down before selecting another. On the ground - YOU'RE the tank, Tac Officer. AoE, threat generation, and group protection are now your job. There is no single DPS class on the ground--your extra damage skills are there to make up for "lost" DPS as a result of your new tanking role, so that your damage doesn't suffer by using Overwatch and the like.
Hold on there are actually Science and Cruiser vessels Engineers and Science people in this game...
damn, i wonder how i missed that... Any answers cryptic?
I dunno bout you guys but im constantly surrounded by escorts
Enemy Escorts don't count... :p
Friendly Escorts are not surprising since a huge majority of the players play tactical.
Without a viable value to healing and buffing, the Science Officer classes will fall into disuse.
The same with the Engineer, most people who play them probably due so for thier suvivability and not to support a team.
In the End the DPS will be the only viable choice, any other role will be effectively useless. This appears to be Cryptic's design. Much like the Defender in City of Heroes, a class that must have been a mistake since the Devs (same Lead ironically) removed any vialble reason to play them, then gave ther abilities to some other archtype.