Very easy to switch the extensions on. Folder options, View Tab, Uncheck the hide extensions for known file types box and click apply. Simple as that.
As a veteran track designer it's a pain in the nether regions to extract somebodies work to use textures or models whether it be to assist in a build or use them for my owner personal designs to see extensions were left off and having to hand rename the files with a .bin extension to allow them to show up in Bin Edit or Traxx. When I first was met with an issue like this I would get model errors in game and in Traxx and couldn't figure out why until I noticed for that particular track extensions were turned off when I went to the model folder or model box in Traxx.
It's a really simple fix and I have to applaud Phin's efforts in getting people to change their habits with this issue. It is crucial to get everyone on the same page so that this game may continue to live long and prosper!!!