We have a couple of "enthusiast" shops in the area. I do not see the traffic in those as I see at the local LBS who is dealing in Trek or Specialized etc. I would think that, purely anecdotal, the majority of sales at any LBS are to non-enthusiasts or at least pre-enthusiasts without the detailed knowledge to know the difference between one derailleur or the next. I would also think as a trade-in, a shop would want to display and sell a bike that was in as stock configuration as possible. If the bike is adorned with this or that custom part, the bike takes on a more personal air about it. Like anything else, once you start to customize something you reduce the market that it will appeal to.