Yes, I have to agree that it's really too bad the original movement is gone. I tend to be a purist, and I don't like conversions like this. I can see doing a conversion if the original movement is broken beyond repair. Although, if this clock had come my way with a broken movement, I'd probably have left it alone, and considered it a decorative object.
Past that, in this case, I really wish the person doing the conversion had put the back on again. While it's strictly not necessary, and it's easier changing a battery with an open back, the outward appearance would be considerably better looking--and more authentic looking--if that back were still in place. Plus, the back helped hold the dial assembly in place. (The dial assembly, which also holds the movement, has 2 threaded poles that run through the case. The back obviously attached to those poles, and would help "clamp" the front to the case.)
At least, the really important stuff--the case and the dial--survived. And, while I don't like the conversion, I might as well use this as a clock, since I can use a quartz clock.
Although, I have been thinking that it would be an interesting project to try converting it back to electric. I think electric movements are probably NLA, but I might stumble across one. Possibly inside a case that is beyond any hope of repair.