I wish that the term "design by committee" didn't have the stopping power it has. Rust's current module system absolutely wasn't designed by committee, and if there's one complaint that I'd levy against it it'd be "overengineered", which is typically what people seem to tend to expect from systems designed by committees!
Personally, whether or not something is designed by a committee is orthogonal. What matters more is whether that something is well-integrated with the sibling systems that it is integrated with (read: unsurprising), and whether its design exhibits good taste (obviously, openly, wantonly subjective, but perhaps we can usefully say that a design can be judged to have good taste if it is so judged by people who think that its sibling systems also have good taste (so read: consistent)).
In truth, there probably is a positive correlation between things that are designed by committee and things that violate the two principles above; it's hard to get lots of people to commit to a consistent vision, especially if that involves serious tradeoffs. It's part of why languages with BDFLs tend to be considered at least coherent, if not elegant: it's easy for a committee of one to have a vision consistent with itself. But where this pejorative doesn't necessarily apply is when the committee is small, close-knit, and all share the same values.
When it comes to Rust, the committee in question is the language team, which is just seven people (in contrast to the dozens of commenters on this issue, who are there to provide perspective and arguments, not to cast votes). Of these, the team lead (Niko Matsakis) is someone that I personally trust to have excellent taste; I feel the same about the RFC author, Aaron Turon, who is also on the language team. And, for better or worse, teams choose their own new members, which gives good taste the chance to propagate; this runs the risk of stagnation (lessened, hopefully, by the RFC process), but also avoids the fractured nature of committees assembled from far afield.
For the record, the module system is exactly one of those things that I've long felt is subpar about Rust (though still better than headers, obviously--that's not a debate, it's a massacre). I haven't had the chance to play with the revised modules RFC yet, but we'll have a lot of experience with it before it potentially gets stabilized, and from what I've read it does look like it ultimately improves consistency and reduces surprises when judged against the rest of the language, which makes me optimistic. I'd love to have to find something new about Rust to whine about. :)
