I think your observation is valid. I could not find one close to Houston and was looking on craigslist for San Antonio and Dallas with no luck. Finally found one on EBay in Austin.
I think a big part of the appeal is simplicity. My friend is scared to tinker with his ecu Indian because touching the  wrong wire can result in a check engine light and a trip to the shop.  
My S40 has been very forgiving during my amateur attempts to tinker.

The number of LS650/S40 bikes for sale on Craigslist appears to have dropped considerably.  It was common to see 2 or 3 for sale at a time.....now I rarely see them listed.

However - there currently are 238 Harleys for sale on the Cincinnati Craigslist!

Seattle/Portland has 4, including an overpriced 2019.
Cheers!  

I am new to the forum and riding but i think you are right. I just got a 2015 s40 for my first bike this week. I absolutly love the bike so far. Im built like a yeti im 6'4" but have surprisingly short legs so i wanted something on the shorter side.

I got my '15 S40 a couple months ago, but it took me a few months of looking to finally find one that was in good shape. I found several that were owned by people who didn't know what they were doing and let the bike get into questionable condition and wanted top dollar for it. The one I finally settled on I had to drive 2 hours to pick up, but it was well worth it. I just finished up a bobber conversion on it and couldn't be happier with the outcome. This is such a fun bike.