Vinyl would still sound terrible if the DJ just puts a microphone against a little speaker and re-amplifies it!
The wedding was in Yorkshire ('nuff said) a couple of weeks ago, and I had a headphone to phono adapter that would have been miles better than using a microphone, but the carpark was a swamp so I thought "sod it - someone else's problem".
In my opinion, people prefer quantity to quality, these days - which is why iPods are even more popular than personal CDs. A DJ will get more referrals based on the size of his hard drive! 400GB of free laptop space will hold 80,000 tracks - a vinyl DJ would simply be unable to carry that variety around with him.