The purpose of the site plan and architectural design review process (conducted together as "site plan review" or "site plan approval") is to produce a harmonious, pleasing and desirable appearance of sites, structures and signs through the review of the site design and building design including, but not limited to, materials, textures, colors and such other elements of construction which affect the exterior appearance of structures; to encourage originality in site design, building design, and construction in a manner which will enhance the physical appearance and attractiveness of the community; to preserve the investments in properties which exhibit tasteful consideration of the external physical appearance of the site plan and structures thereon; and to encourage and enhance the desirability of private investment within the surrounding area.