Anyway, I'm confused by the OP. I'm also confused as to why she has 4+ upvotes. Stating "we need more dps" can be said in a few ways. But how it is stated by the OP it doesn't seem like the healer was actually being rude, mean, or insulting just that they were stating a fact: the team needs more DPS.

Many (all) bosses will eventually wipe your party if you take to long, because of MP/TP concerns and cooldowns, over run by adds, enrage timers, or player fatigue (if it takes to long and players start messing up). ALL of these are countered by having enough/higher DPS to kill the boss in time. Stating "we need more DPS" isn't always to attack the DPS, though usually it happens because the DPS isn't doing correct rotations (lazy or clueless) or they aren't utilizing their full kit. Healers and Tanks are less at fault, but they can still bring some DPS.

So long as the Healer was DPSing as well (if they could. They actually don't even have to do this, but whatever) they actually have a right to state that the team doesn't have enough if things are going poorly because of it (not bad tanks, heals, or mechanics).