Scripture scholar C.H. Dodd famously said that a "parable is a metaphor or simile drawn from nature or common life, arresting the hearer by its vividness or strangeness, and leaving the mind in sufficient doubt to its precise application—to tease the mind into active thought."
This is pretty obvious about the parables: they confuse you a little, they make you think, they turn your view upside down. But don't underestimate Jesus as an expert teacher who does the same kind of thing to make you think even outside the parable format. Think of Jesus and Caesar's coin and the question about the census tax. He uses misdirection and a sharp one-liner to dodge both the pro-Romans and the anti-Romans and to get to the heart of what the people should being doing with their money, their lives, and their allegiances.
The same thing happens in today's Gospel. Jesus isn't disrespecting his mother; he's getting you to gasp as what he said to challenge yourself about how seriously you take his work. Same thing for the man burying his father. And for the status of John the Baptist.
Jesus is the perfect instructor. If he's hitting a nerve, it's probably because you've had your nerves deadened for awhile.