In my experience with communication theories, I have found the majority of them to be extremely useful tools in understanding human behavior. Learning about these theories have almost always been an enlightening experience that often results in that "aha" moment of realization that I'm not alone in my experiences.
Take for example social exchange theory; I often view the world from an economic standpoint, so the cost benefit analysis of relationships was interesting to learn about as I applied this same mindset to my romantic relationships. In the past I would examine situations like "is it worth the fight", weighing the costs and benefits of having an uncomfortable conversation. This has helped me better understand how I operate personally, and improved my ability to diagnose and analyze relational issues so that I can remedy them.
There are, however, theories that I see less use for, particularly theories that fall under the critical paradigm. This may be because I am in the highest privileged category as a white middle class male, and therefore relate the least in terms of my understanding of the theories, but I also don't tend to see the same accuracy in its application to real life situations as I do in the observational theories. For example, I tend to fall in the camp that believes discrimination has less to do with physical makeup such as sex, and race, but rather socioeconomic status. That's not to say that sexism and racism are not still present; however I do think their rampancy is overstated.
I think there is a lot of practical value to these theories as humans are social creatures. Communication is a key facet of our lives, and is useful in our careers, in our relationships, and to ourselves. The better one understands something, the easier it becomes to master; mastering communication is a life skill that a great deal of people would love to have. Adding communication to the curriculum of high school, or even middle school education would help millions of students who struggle to communicate effectively learn why they are struggling, and how to improve themselves. It would vastly improve our generations ability to work with others, as well as become more comfortable in their own skin; at least that's what communication has helped done for me.