It might be helpful to follow a strand of British empiricism and to think about 'morality' as a social phenomenon, involving various 'sanctions' such as blame, guilt, shame, and so on. (So in that respect it is rather like law, though the sanctions there are somewhat different.) Your worry is that some moral principle you accept -- that it's wrong to cause serious suffering merely for fun, say -- has emerged only because of the evolutionary advantage conferred on groups which accept something like that principle. So it seems quite contingent which principles we come to believe -- as you imply, in different circumstances we might accept different principles. But, to pick up Alex's point, we have the capacity to stand back from our 'morality' and assess whether we have independent reason to accept its principles. In which case, if you believe there is a reason not to cause suffering for fun, you may think that this justifies the moral principle which forbids it (as it would also justify a law forbidding it).

There must be a middle ground as far as the status of buildings is concerned -- they can be viewed both functionally and aesthetically. And of course it is a common criticism of a building that one aspect has been overvalued at the expense of the other. Such criticism shows that we can see architects from the same two perspectives, so that we can condemn an architect either for failing to provide us with an effective building (the architect and her skill being viewed almost as mere 'means' to our ends), or for putting up something ugly (in which case we are casting aspersions on the architect's aesthetic capacities). What one must remember also is that one might admire the skills an architect shows in producing a particularly effective building, so that architectural activity can be both an end in itself, exemplifying certain excellences, and directed towards an independent end (a building). Aristotle puts this point especially clearly at the beginning of the Nicomachean Ethics.