I personally don't use CircuitLab and wouldn't use anything else you add either. That's because I'm quite comfortable with Eagle and have created some scripts and procedures for getting schematics from Eagle into posts and have the result look nice.
However, I've seen others use CircuitLab with good success. CircuitLab schematics are always more readable than anything else posted by the great unwashed masses. Anything that helps people draw neat and readable schematics here is a benefit. Whether having a second schematic editor would increase the average quality of schematics posted here, I can't guess. I don't see how it can hurt, though.
One problem I see with CircuitLab schematics is that all too often people get lazy and grab a symbol for a similar part without updating its annotation to the actual part they are using. This seems to happen particularly often with opamps. Particularly we see TL072 shown in place of whatever opamp is really being used, with lots of collective time wasted as a result. I have never even tried to use CircuitLab, so I don't know if this is due to some flaw in its UI that makes it difficult to find the right part or to change the value of a existing part, or just laziness of users. If a new circuit editor is added, this might be something to address deliberately.
I'm not sure what I think about the simulation capability of the new proposed schematic tool. The primary advantage is to have neat and readable schematics. We might get more of them if people could easily post a schematic from a simulation.
However, I'm worried that simulation will become more of a crux for the incompetent than it already is. The schematics I've seen here that came from simulation programs usually look like a mess and tend to have various annoying things scattered about that are apparently droppings from the simulation. If the new editor makes it easy to post just the schematic with simulation artifacts removed, then it might be useful.
Another problem is that question are usually more tedious to answer when the OP has done a simulation but doesn't know what they are doing. They tend be more likely to latch on to nonsense beliefs that have to be dispelled before the real question can be answered. I often just skip questions like that as being too much trouble. I'm worried that the simulation capability will cause more questions of this sort.