No CDR
Q - 6
W - 18>10
E - 14>8
R - 40>24
Alright, let's have a look. The above are her listed cooldowns. I think it is a fair assumption to say that Leblanc will at least get a Deathfire's Grasp in a game correct? Perhaps even an Athene's while the 5% CDR from masteries is a given. So at the very minimum, assuming only a DFG and masteries she would have 15% CDR in the late game without a blue buff on.
Min CDR
Q - 5.1
W - 15.3/8.5
E - 11.9/6.8
R - 34/20.4
I dunno, those numbers look pretty reasonable for an AP assassin to me. Even more so considering she has an ultimate with such a low base CD anyway. The only ability I would say has a long cooldown is W but that's intentional. It is meant to be the mobility spell and should have a long base CD while being her longest CD non-ultimate. Even then, with minimum CDR it is 8.5 seconds. That's very reasonable considering you can jump twice per cast and snare someone for up to 3 seconds.
If you're still maxing W and wondering why you can't kill, then I can't help you there cause that's working as intended. Maxed W yields the lowest burst and has never been the optimal damage skill order anyway. People were maxing W first to make up for LB's shit wave clear and to give her more mobility, sooner. If you need a professional player's backing, Froggen has stated this back when she was a popular pick competitively.
If you wanted sheer power ASAP, Q has the most as a first max. Even so, it is not technically allowing maximum damage. Optimal first max would be E since it snares and allows you to also get AA damage in. Assuming you used W only for the close, a Q > R > E would be your best bet for sheer damage output just from abilities. If you aren't afraid to take some pain back, then Q > E > R is better because you can chain slow into double snares. Her snare has a tether range of 1000 and a cast range of ~700. If you are unable to take advantage of that, again I can't help you. That is ludicrously long given that it is her 2nd best damage non-ultimate ability.
Compared to LB:
- Nocturne has a fear tether range of a measley 465
- Karma's snare cast and tether are only 675
- Fiddle's Drain has a cast of 575 and max tether of 750
- Morg comes close with a ~600 cast and 1050 tether, but that's her ultimate
So please, LeBlanc isn't weak. Her cooldowns aren't bad. So what if she isn't popular anymore? If you like her, play her. She got changed and what people used to do all the time doesn't work anymore? *gasp How is this possible? If it ain't working then try something different.