OK, look, if you put it like that, I can sympathise a bit. I was one of the biggest proponents of Nidalee's Q being nerfed and I HATED hearing "just dodge the spears" because it was a fucking stupid argument- Javelin Toss was both the longest-ranged AND highest-damage nonultimate ability in the game and dodging them was futile because it had a 6-second CD and if you were hit by even ONE you'd be lucky to not die instantly unless you were tank-built. But Lucent Singularity is NOT Javelin Toss. It has a longer CD, MUCH higher mana cost and considerably lower damage than a max-range Javelin (240+60% AP at rank 5 vs up to 390+120% AP for a rank 5 max ranged Javelin). She might whittle you down with several of them, but she's burning her waveclear (and RACING through her mana) to do so. Also, you CAN juke Lucent Singularity- if you're moving and not already in close range to her she has to lead it, and if you change direction she'll whiff it. And if you're 1 hit from dying you can simply Flash it, so it's simply not a point-and-click. Comparatively easy to hit with, OK, sure, but it's hardly game-breaking.
Besides, what exactly are you asking for here? The projectile to be slowed down? There's a very fine line there, and if they make it too slow Lux will simply be unplayably garbage because you won't be able to land her E on a non-CC'd target at all.
Incidentally, did you know Javelin Toss still has a range of 1500 and the same 1300 speed as Lucent Singularity? Yeah. "Just dodge the Singularities."