RSS Feeds should have thumbnail built in, as much as categories and tags.
The idea will be to stream your blog, stream some other blogs or feeds you are likely to interact with (like, share, repost) and have the ability to pull out Thumbnail image, tags (# will be automated while sharing a post to your twitter account), categories will work the same. FYI some wordpress plugin does it, pull out your blog with proper tags so why not Hootsuite with a stronger RSS feeder?
Being able to see your RSS feed titles is handy, but having that thumbnail image to go along with it is key. Would be amazing if that could be added in
This a no brainer... Obviously feeds should pull thumbnails.