Corvettes are only good at taking out unprepared tacs. Any tac cruiser worth their salt can shut down most corvettes in the area provided it is built well (in particular the light tac). The corvette is an assassin; good for taking out weak / lone ships. It can only get away with diving into a team to take out a ship if the entire enemy team is somehow oblivious to its presence, usually due to being focused on the other team. Better targets are the artillery cruisers that sit, at worst, on the back edge of their team, and at best, out in the middle of nowhere miles away from any support.
When it comes to taking out a tac cruiser in the middle of a team, a destroyer really is the way to go. Much better equipped for the job.
As for rewarding players for kamikaze-style play... no. If you do manage to take out one of two healers in your suicide run, chances are the enemy team can still hold out until the second healer respawns and gets back into position. All that you've done is given the enemy team a kill for getting a kill for yourself; greedy play that does nothing for your team. The good 'vettes are the ones that can weigh risk vs. reward and get several kills between deaths.