I often find that people who haven't had a child ask the most inappropriate questions. I put it down to lack of experience. I should know I was one of them once upon a time. Some questions I used to ask I would never dream of asking now.
I totally agree with those sentiments... being on BB has taught me sooooo much about being more tactful (probably has a lot to do with the fact that my mother is probably the most tactless - and now I just see it as downright rudeness rather than meaning well but missing the target, kwim? - person I've ever met, and unfortunately I was raised by her so it rubbed off), especially when it comes to the more painful parts of parenthood, like the right and wrong things to say around those who are TTC, have had a loss, had a less-than-desirable birthing experience etc...
When you don't have kids, you just don't 'get it', I suppose a lot of times people are just trying to express an interest in you and the kids and they kind of fumble a bit, kwim? Say the wrong thing without meaning to, because their intention was to get a conversation going or satisfy their own curiosity, rather than put their foot in their mouth, so to speak

I do get those kinds of questions a lot, but I'm one of those motormouths who has no qualms about sharing the gory details, whether it be putting the fear of God into a childless person by describing how I nearly bled to death giving birth to DD1, or bragging my backside off about how fast and easy DD2's birth was I can definitely understand though that for a lot of people, these kinds of things are off-limits as far as 'casual' conversation topics go - I mean, I don't particularly care to hear about, say, an acquaintance's sex life, nor would I wish to discuss mine with anybody but my absolute closest friends, so I suppose it all depends on the individual as to whether they're comfortable talking about certain things with certain people.
That being said, it does also depend on how the questions are worded - and yes, I would be a bit miffed if someone I wasn't close to used the type of wording you put in your first post - it may be a more 'informal' way of asking the question, but for those who haven't 'walked a mile' it can be quite offensive... so yes, the wording of the question itself, or the intended meaning behind it, would also determine whether I would be comfortable opening up.