Because landscape photos are easy. No bokeh, no depth of field (everything at infinity), good lighting, no need for fast shutter speed or a big sensor. Your images will be sharper I guess, but that's not worth $2k in most cases.
(Which requires a lot of patience, but an old one would be cheaper than a new camera. Though renting is always an option.)
edit: changed "sensor sizes" to "sensor areas" for clarity.