I worked 30-years for CAA/FAA in the technical side in towers, flight service stations, three different ARTCC facilities, and RAPCON. I am a private pilot also.
The thing that I find not good in tower communications (comments are re towers only) is that there is a tendency to speak at a machine gun rate. That really makes understanding more difficult, particularly when at an unfamiliar airport where things are different. Fast speech does not make a controller a 'hot shot', it makes him/her less professional in my view. In years in ARTCC I have never heard this rapid fire speech, it seems only at towers. Its done far, far, too often, even when there is no need to rush things. I have encountered this at towered airports when I was the only plane in the area.
I know this rant won't help much, but it needs to be said.