Agreed, Lights will be useful and can be crucial for flanking etc., but how many of those players who picked light op on the poll above know that they might be at a disadvantage in health, and also believe that they are ninjas with guns and that they are invincible.
I don't think that's something you have to worry about too much. I'm sure the majority of people who voted in this poll already knew all the strengths and weakness of their respective size and class, thus far. All people who voted for the lightweight should already know that flanking and ambushing is their best choice for kills(maybe even their only) and being a lightweight shouldn't be about getting kills in the first place. I could be wrong though, and it would be hilarious to see a light think he can easily dodge a heavy with a Gatling gun by skipping about on the buildings xD;
The way I see it, the reason so many people flock to the light operative is because the lightweights will be using stealth the most to kill enemies and carry out their objectives, since they have such low health and a weak, limited weapon choice, So if their going to be stealthily the majority of the time, might as well pick the class that suits stealth gameplay the most out of the four.
I personally chose light operative because I want to take full advantage of the SMART system(to be a great support to my team with huge speed and parkour efficiency), always preferred the use of stealth in online shooters to kill enemies and carry out objectives, and the operative's recon abilities suit my stealthily play style the best.