Juan – another time! You should see me in lycra!
1) the Mavic (or other) support vehical would have a nitemare trying to get the wheels to fit your bike without the disc rubbing (any long term bike mechanic on here will vouch for that, as even same model hubs from the same manufacturer will occasionally rub the disc when swapped)- so that would cause really issues.
2) The danger aspect. Yes a spoke could cause injury, but they arn't as dangerous as a red hot (at bottom of decent etc)spinning piece of sharp steel.
3) Where are you going to use these disc brakes? coming down a mountain pass? Well you'd have to go up it first and the riders want the lightest wheels possible, so ad to the weight of the wheels a disc plus the extra spokes needed, as you can't run straight pull spokes with discs – so there go's your lightweight wheel set! (yes the rims could be a little lighter, but only by a small amount.
4) loss of areo advantage – as your now running a 2 or 3 cross spoke pattern so you'll be getting dropped on decents, not going faster due to being able to brake harder into corners (which isn't a problem anyway)
5) integrated implication – as far as i can see only the likes of cannondale would attempt it – cos they are a bit 'special' like that.
6) They just ain't needed
1. Good point.
2. Still moot IMO.
3. Doubt it will add that much weight or slow you down
4. 3. above x 1000
5. furry muff.
6. for racing pros maybe, still real benefits for all weather bikes.