I have long pondered this question. A good four years, to be precise. This question first struck in my head around the time when I was increasingly disillusioned by the term landscape photography and the content within it. I used to (and still do) photograph landscapes (everything that is natural) mainly for the joy of it. If I have to delve deeper, this was always a means to pay homage to the most beautiful thing in this planet, the natural living world. The appreciation for nature is universal, and the qualities it brings to people's lives, physically and emotionally, remain undeniable. (The fact that some people need this to be reminded, is a different story in itself.)
Well then, what constitutes a good landscape photo? Is it the landscape: a scale on how stunning it is, the uniqueness of the view, or the eye of the photographer? While a common answer would be: a combination of all the above, I have come to realise that people get struck by photo of a beautiful landscapes (read scenery) even if it is not captured very well. It is also true that you can create good landscape photographs from anywhere. But if one has to adopt it as a practice, it might be a good idea to be living close to geographically-gifted locations just so that the access to good vistas is always easier. The probability (or frequency) for good landscape photos would be much higher. My question about this has always been: Doesn't it make a few individuals, more privileged than the rest? Does it cease to become an art form?
I think this is where the eye of the photographer matters. The emotion one can bring to the images and the ability to convey the poetry, through representativeness or metaphor. A landscape experienced, or changed, or the associations within it, has a lot of potential to be expressed as a visual narrative.
Some might argue that this would no longer make it a landscape photo. I think that is the whole point of art: blurring the boundaries. Genres and disciplines have been created and differentiated for ease of classification for documentation and commercial purposes. Art has no obligation to fall strictly into any of it. If you are having a hard time explaining a work of art, it is already a good sign; an indication that there is a lot more to it: underlying meanings, subjectivity of one's own perception, and deeper questions raised.