Those sorts of tilesets often have more appeal than the kind that look like they were run through a ton of photoshop filters. It really depends on the art style, and of course quality. For example, this tileset has a sort of look which I think really suits JJ2 well. It's also Gus's best tileset so far: if you look at his older ones, they tend to use a lot of "texture" effects which often look out of place. Actually, it's probably the best tileset I've seen since Gothic Cathedral, which is from 2008. That one also has a similar style.

For the issue of eyecandy, a good idea would be to design the tileset in a way that allows for some versatility and creativity on the part of the level maker. That way the person making the level can create much of the eyecandy for themselves... often the best tilesets work this way. For example, cooba's Waste Treatment Facility doesn't have a huge amount of stuff besides basic blocks/pipes, but it's possible to make a very good looking level with it just because the tiles it offers can be used in a ton of different ways. BlurredD's tilesets are also an example of this.

Even though I haven't seen anything of your tileset, good luck with it. You've picked a unique theme and seem to have good ideas (and a focus on gameplay elements) so there's decent potential already.