Professor only teaches what is already in textbook. Should I quit going to the lectures? I've become quite upset with how lectures for my courses are conducted. 

Everyday, I attend lectures where the teacher simply writes definitions and theorems on the board straight from one of our textbooks (or another professor's published lecture notes). They then prove a handful of the theorems, or part of them, and leave more than half as an exercise. They do little to motivate the material or provide insight based on their professional experiences, and are often scribbling material onto the board as fast as possible to cover some predetermined amount. And sometimes the professor writes proofs straight from their notes and, when questioned, has a hard time explaining the gaps between steps (as they are simply regurgitating and not really even attentive to what they are explaining).

Ultimately, I feel like these lectures are a waste of my time. To be blunt, I can read a book and I can do exercises. I don't need someone to paraphrase a book for me and then tell me to fill in the rest myself. Moreover, since I cannot afford to live on/near campus, I have to commute an hour each way to sit through such lectures, which hardly seems validated.

I would like to attend lectures where the professor engages the students. Often, my professors are so rushed to scribble things on the board that they take few questions and relegate them to exercises (yes, I had a professor answer a simple question about his proof by assigning it as an exercise). If an instructor wants to cover some predetermined amount of material, I would prefer they assign this as reading beforehand and then take questions on that material in class. It'd also be nice if they presented us with hard problems in class and then we all worked through them together (with students presenting them, everyone critiquing, etc.).

Should I approach my professors about my feelings? How should I go about this?

To be honest, I am becoming quite bored (and frustrated) and starting to skip lectures in favor of office hours (which are far more engaging), reading the book on my own, and working extra problems. I do not like that I am not enjoying my educational experience (since I love to learn math!).

Or should I quit going to lectures and move on to doing what I am tending towards now, anyways?
This is a common frustration faced by college students, especially in lecture-oriented STEM majors. Unfortunately, the truth is that the lectures may be a waste of time and there is little you can do to change that. If you can cover the material more efficiently on your own time (especially since you're commuting), you shouldn't necessarily feel guilty in doing so. You can see similar sentiments expressed on ratemyprofessor where students often question the value of lectures and simply go to the library as opposed to lecture. 

Yes you're paying for the lecture, but if it doesn't help/contribute to your understanding, there is no point in going. I knew students who went every time out of habit, but it was an absolute waste of time. 

I've had physics professors who wrote starting problems on the board and then the solution only to say that if we were at his level, we should 'see' the dozen steps in between. Needless to say, lectures were fairly empty after that. He was very well versed in the material and many students would come to office hours, it's just that he couldn't lecture.

Depending on the age/tenure of the professor, they may be receptive to making the lectures more engaging, or they may "brush" you off. Simply express your interest in the subject to the professor and ask them to make the lecture more engaging/be better prepared. Depending on the college/class, the professor may be unable to accommodate you because your peers may not be at your level. Be aware that some professors cannot lecture effectively, or have had unwanted courses foisted upon them. No matter your school ranking or major, you will encounter lousy enthusiasm-killing professors whom you'll have to endure. For many professors, your best shot for a more engaging experience would be to visit them during office hours.

In a certain sense, to quote Mark Twain, "Don't let schooling interfere with your education." You won't have this professor forever, though you may unfortunately have them or those like them again. Don't let them dampen your passion for the subject.