Sorry TangoAlphad and wiggy, I'm afraid I just don't buy it. The fact is that, whatever the reason, the flight is delayed, end of. Adding some useless generic reason is adding insult to injury. Do you honestly believe that announcing my flight is delayed because of the late arrival of the inbound is going to make me feel any better? Just tell me my flight is delayed until whatever time and leave it at that. As already mentioned, it is my experience that the Captain usually provides a better explanation with a PA once boarding is completed, and it doesn't have to be as detailed as TangoAlphad's amusing example. Fortunately at many airport these days we only have screens to look at and, thankfully, we don't have to listen to announcements using those ridiculous and useless generic reasons.