I'm making a historical research on the origins of differential geometry, starting with non-Euclidean geometry introduced by Gauss. Reading different historical accounts, what I don't understand is how far mathematicians were motivated by a merely abstract and theoretical line of research or if the study of non-Euclidean geometry was also motivated by some pragmatic motives. Gauss was busy also doing geodetic surveys, but that was still Euclidean geometry (right...?). As far as I understand it, Gauss did not have in mind any applications of it (like, much later, will happen with Einstein's general relativity). On the other hand, it is clear that he was not just interested in solving the problem of parallel lines, but he (and many others too, like Riemann, Lobachevsky, etc.) were busy in developing an entirely new geometry. Moreover, according to Wikipedia "Gauss also claimed to have discovered the possibility of non-Euclidean geometries but never published it." Today, for us, a manifold in an N-dimensional non-Euclidean space may sound like an established mathematical object with obvious applications in physics, but I feel that at the time of Gauss that must have sounded like an absurdity to some.
So, the question is: What was the real motivation that stood behind the development of DG? Or, rephrasing: At the time of the birth of non-Euclidean differential geometry, what was the general perception about it? Did they perceive it as a fascinating but mere theoretical abstraction, or were they driven by some other theoretical and/or pragmatic necessity?