people focus on edge cases because when you start with different common cases and extrapolate them, they contradict each other. the edges cases illustrate the contradictions, but they are firmly rooted in common situations - if they weren't, why bother with them?
for example, it's common to ask whether someone would divert a train onto another line, knowing it would kill someone, to save some larger number of people. that's interesting because two heuristics we use in common cases are (i) avoid doing something that would harm another and (ii) minimise the amount of suffering.
in that case it's not that anyone thinks it's particularly useful to discuss trains because trains are such fascinating things in themselves. instead, it's an interesting case precisely because it shows how starting from two common rules can give contradicting answers.
The trouble with all of these questions is simply that they are designed to force a big contradiction - and whatever answer you give the questioner usually has an "aha but....." ready for you.
The issue is that these problems are never "real world" and so are irrelevant to any actual discussion. Contradictions are, clearly, problematic - but only if we are going to face them. Until then they are just interesting diversions (pretty much like all of capital-E Ethics)
I'm not sure there is a real world problem that is completely morally insoluble.
for example, it's common to ask whether someone would divert a train onto another line, knowing it would kill someone, to save some larger number of people. that's interesting because two heuristics we use in common cases are (i) avoid doing something that would harm another and (ii) minimise the amount of suffering.
in that case it's not that anyone thinks it's particularly useful to discuss trains because trains are such fascinating things in themselves. instead, it's an interesting case precisely because it shows how starting from two common rules can give contradicting answers.