One can argue that a photo reference is but a tool, a point from which the artist departs to make their work, that outright copying is the bad thing... But if so, what percentage is acceptable? 20% reference, 80% by eye? 50/50? Does this mean Chuck Close's early, more photo-realistic work, is less "worthy" of praise than his more modern pixelated approach?
If one assumes that art that uses a photo reference is less worthy, then masters like Picasso, Degas, Muncha, Cezanne, Kahlo, and Eakins were purveyors of schlock for daring to use photo references with varying degrees of copying.
If an artist receives a commission to create a portrait, is it somehow less desirable for them to use a photo, or, god forbid, trace a projected image? Is it more desirable to just force the subject to sit for weeks on end to labor through the process with the artist?
And what of photography... is it art? Is it worthy of such a lofty title? I would defy anyone to say the work of Ansel Adams, Dorothea Lange, or Jerry Uelsmann is not "ART."
The notion that gridding, or the use of photo references is "less artful" is ignorant. Nor is it an insult to photography to do so. Surely an art program can be successful without the use of photography and gridding, as would a music program without the mention of Philip Glass and the minimalism movement... but such programs would be incomplete.
The opposite is true as well, as grids and photo-references can become a crutch, and too much Philip Glass may make one go mad... A broad art program should expose students to many techniques, media, and approaches. I believe that IF a student uses a photo reference it should have some personal meaning, interest, or expressive quality, otherwise it is less "artful" because it may lack personal expression, a key component of art. Better still is to work from an image they have composed and created. With the proliferation of cameras in cell phones, this may be easier than you may think. Districts are certainly pushing for more technology integration, and this is a golden opportunity. Students may in fact prefer the photograph, but should they choose to translate that image into paint because the idea pleases them, then who should pass judgement upon such a choice?
It's not a insult to photography, it's a choice to use the image as is or as a tool to complete the artist's vision in the media they decide to use. The very fact that it is being re-created in another media means the hand of the artist will exist within the work, making it unique, either subtly or overtly.
The practice of gridding, not only improves the quality of student work, and provides students with another of many tools they can choose from, but it is tied to geometry, measuring skills, history, concepts of scale and proportion... all things that are important across the curriculum. Art is not an island, but the meeting place of all subjects.
All this, and the joy they get from doing something they thought was beyond them, saying out lout, "I did that!? Awesome!" Though not all succeed, there is value in the experience on many levels.