I am a software developer and I have a job with which I am quite happy. However its not perfect, and there are things which I wish were different, such as a shorter commute. Recently I have had a company want to interview me, which is local to where I live, everything else about the job appears similar on paper. I have already mentioned to the recruiter than I am not really actively seeking to leave my current job but I would be willing to attend the interview.
So my question is, how do I attend the interview and not appear uninterested? How do I convincingly reply to the question of why I want to leave my current role? I do not expect to get away with, "erm.. I do not really but I just wanted to speak with you to see if your company could be a better fit" or "I want to have a shorter commute".
I feel this could put the new company off. Other reasons include slightly newer tech, greenfield projects, and mobile development in addition to web, which I like. But again, none of these are critical to me.
Edit: I am getting some comments along the lines of "don't go if you are not interested". So to clarify, I am interested, thats why I am going, but there are levels of interest. My interest is to find out if the company is similar to where I currently work, can offer me the same benefits and also is a shorter commute. But I am not interested in the way someone who does not have a job is.