I have this issue too but more so because I feel like I am just adding to the noise when I don't have anything more substantial to say other than Thank You. "People are already overloaded with the amount of emails they get, do I need to it?" is how I've looked at it but perhaps but that's not the best approach.
This is true as well. I don't really like receiving emails that just say 'Thank you', and I'm never sure whether other people do or not. Some relatively high-profile and busy people have said to me in the past "Did you get the thing I sent? You didn't say thanks." so it's definitely a personal thing.
