Siri will ONLY respond with uh huh, if you pause after calling Siri's name.
Example: Hey Siri........................................Uh Huh? Then you ask your question
Instead, do NOT pause after waking Siri.
Example: Hey Siri, what is tomorrow's weather in Sacramento
In the later example, Siri will not say uh huh. It's all about how you speak with Siri. Just like if you tried to ask me a question, but paused after you said my name, I'd like say something like uh huh, to see if you still wanted to ask me something.
It is NOT rude. It's a normal expression, especially when you pause after invoking Siri.
But sure, you don't have to use Siri. That's entirely your choice. And one no one here on this user to user only forum would really be bothered much about.