Noo way, SE damage is pretty good. I typically outdps everyone in instances! Maybe not if they are totally geared out, haha, but I usually do way more dps. I think it depends on how you spec really, maybe I've been playing with bad players lol.
SE in PvP is great really, if I had the points I would max out my stuns. The stuns together would be like 8 seconds maxed, which is more than enough time to completely destroy whoever is may be. Also since we have detect we get those kills from SWs that other classes don't see.
Long range means standing on top of crates in Janus (Of course a whipper can hit you from there or pull you off) but still make it harder for DE and SW to get you (Sometimes SE and PU might say that an obstacle is in the way if they're too close).
SE slowing skills are very very useful in PvP as well since they will be much slower and you are a faster class, able to run away while stopping to shoot occasionally if you need to. Yes, SE are a bit squishy but just like DE if we have a good Medic by our side we are pretty scary, especially with Rare Mech AoE stun.
But yeah, in PvE SE's are just as great, I used to be all PvE spec (Until I came to my senses that this is a PvP game) and my damage is great. Especially if a SE maximizes on the fact that they hit Chakra damage with everything, including their auto attack, they can crank out great dps. It depends on how you play it, but that's for every class. I only have pros to say since I love my SE.