Which users? I only ever use curl to print stuff to stdout, but I use it for that a lot. When I want to download a file as lazily as possible, I use wget.
If you don't use the tools often enough to remember how they work, I don't think your needs are going to come up high on the developer's priority list.
Turns out it depends on which tool you learned first (my case and many others mentioned here). I'm not ashamed to say I've always used cURL for everything and never installed wget. wget is awesome but cURL serves me right. I do a lot of HTTP and API stuff so I only need the headers most of the time. If I want to examine the (usually) JSON output of a call, I pipe to a custom alias that combines pygments (http://pygments.org) and `python -m json.tool` to beautifully format it. (alias pretty='/usr/bin/python -m json.tool | /usr/local/bin/pygmentize -O style=monokai -f console256 -g')
That's my approach too. But he wrote himself "a very common comment to me about curl" - if someone actually finds the time / motivation to write to him about this difference, I'd count them as a user.
Maybe they count as a user, but they count comparatively to all the people who don't write him. I'd hardly expect him to get tweets and emails saying "It was so great how your tool printed what I wanted to stdout", even in cases where people do prefer that.
It's tough to get a representative sample from something like voluntary correspondence, because it doesn't tell you the majority opinion, just the majority opinion from people who decided to write in.
EDIT: To note, it's entirely possible that the silent majority of curl users really do hate the default-to-stdout choice. But absent a real way of surveying, it's difficult to make a call either way.
If you don't use the tools often enough to remember how they work, I don't think your needs are going to come up high on the developer's priority list.