"Point and Click" stun does not mean the same as "Click and Melee Attack" stun.
An example of a "point and click" fear would be Fiddlesticks. You point your cursor at the target (the "point" part) and you smart cast his Q (the "click" part) and the target is feared. Renekton DOES NOT have a Point and Click stun. He has to melee attack his target to stun. That requires certain conditions to be true and therefore allows for some counter play. Certainly more than a "Point and Click" stun would allow. Veigar's stun is point and click. Renekton's stun is not.
Sustain is a pretty common mechanic in LoL. Dozens of champions have some form of sustain in their kit. His sustain is fairly weak unless he uses it with fury. Even then he really wants to use it on champions for the extra % healed (it's 40% of damage dealt when used with fury against champions compared to only 5% of damage dealt when used without fury against minions). I'm not saying his sustain is poor, I'm just saying it's normally increased with a doran's blade (which provides decent health returns on it's own).
His stun is short duration -> 0.75 seconds, unless you use it with fury in which case you'll lose a lot of damage and it's only 1.5 seconds worth of stun then. It's not that long a stun either way.
He has no "real" range on his abilities making him basically melee based.
He does have a gap closer though, let's talk about that. His gap close ability is fairly short ranged (450) and can be used twice if it hits something. That's a decent 900 range if you can get something between you and your target. Worst case scenario it's only 450 which is well below average. Best case scenario it's 900 and well above average. Either way with champions coming out with multiple gap closers (Vi, J4, Lee Sin, etc) now ... Renekton isn't look that special. Also if he's using it twice just to cover ground he's losing out on damage. Plus it's got a decently long cooldown on it.
I think part of the reason why Renekton is doing well is that Doran's Shield got nerfed. This moved the advantage to Top Laners who do well with Doran's Blade (the other common strong pick for early sustain in top). In my opinion, I feel Renekton is one of those Top Laners who does well with Doran's Blade. Furthermore Doran's Shield was a really strong pick against Renekton players (before it was nerfed) but with it's reduced effectiveness now (after being nerfed) it feels more like a trap. It's the only Doran's item that's gold inefficient (based on it's stats alone - ie: not including it's passive).
