No.
You're already "rewarded" for choosing a heal/tank role with a shorter queue. You don't need to penalise people who want to DPS more than their enormous queue already does.
Besides, on a practical level, do you really want [even more] DPSers who have no business tanking or healing trying to do so in your raid to avoid penalties? Groups are bad enough in LFR, we don't need that too.