I don't object to it in principal. At 0.7% GNI, the sum is a very small proportion of our overall expenditure and because the pound is comparatively strong relative to less developed economies, those sums are capable of 'doing' far more in Nepal or China than the equivalent sums would do here. So it's an extremely small sum that has the potential to do a lot of good which would make a relatively small difference if it was spent here. It may seem like an extravagance, but if done right (an important 'if') it seems to me a more sensible way to try and make the world more secure than (say) chucking a handful of expensive missiles into long-foresaken warzones.
Of course, that's all subject to a long list of 'ifs', and foreign aid at its worst can of course bolster awful regimes, participate in global corruption networks and make the world worse. All the information on whether or not British foreign aid is a force for good in the world seems to me highly partisan and sensationalist, so I'm unsure what the truth is. If our foreign aid bill is misspent or mismanaged, though, I would prefer to improve the problems with it rather than scrap it altogether.