The crafting of spaces can be either utilitarian or aesthetic. during certain periods of our history, the two differing viewpoints have converged, such that the spartan utilitarianism has been viewed as aesthetically pleasing, such as Bauhaus. Then at other times, the opposite is the case, such as Baroque.
We're always taking our cues about how we should feel about our surroundings from the context. We permit a shopping centre to be utilitarian, whereas we allow an opera house to be Baroque. But when the two cross, we have the makings of a unique experience. I'm not saying this is the only reason why architecture is interesting, but it's one of the things which catches my eye; how has the design been influenced by its function, versus how has its design influenced our feelings.