Let people choose what exporters to install, for example ATM I don't need:
Tizen, BB, Arcade, Win8, Firefox, Webkit Linux.
I believe the exporters are small enough that it doesn't really matter. The exporter just wraps up the runtime.js, and provide an index.html as needed. It's really tiny.
Develop games in your browser. Powerful, performant & highly capable.
jayderyu is right, an "exporter" is basically a slightly different HTML template and a few tweaks to the normal export process. There would be absolutely no benefit to omitting every single exporter apart from one - Construct 2 wouldn't be any faster or quicker or anything, it would be exactly the same.