Can a Doctor fire a patient for making a suggestion?

About a year ago, I went to my optometrist for a mandatory contact lens exam so I could order more contacts. I was required to complete a plethora of handwritten forms - most of which included duplicate information from the previous form. I thought it was inefficient compared to other physicians I've visited who have online forms with saved information that simply lets you note changes since your last visit vs doing the whole thing over again. I made a suggestion that she make the form process more efficient and less time-consuming. I took great pains to present the suggestion in a constructive and neutral tone. I anticipated a response something like "I'll consider it" or something similar. Instead, she took exception to it. We had a civil back-and-forth debate over the next 60 seconds or so. She became defensive. She appeared perturbed at the idea that I would suggest such a thing. The message was clear: I had the gall to make such a suggestion, inferring that her clerical system was beyond reproach.

A few days ago, I went back for my yearly exam and was booked for an appointment by an assistant. The next day, I received a faxed fill-in-the-blank form letter saying I should seek service elsewhere.

The fact that she uses a form letter implies she does this was some frequency.

Question: What are my rights as a patient?