@Kovid - yes indeed, adding to the wizard would delay users getting to the "good stuff" by a couple more clicks.
However I do have some recollection of my first time experience of calibre since it was less than 18 months ago, and it was
very frustrating. To the point of more than once googling for alternative products so I could uninstall it. Since I fall into the technical user category, I ended up posting in these forums about some of the various issues I had - author sorts, not a clue about "plugboards" etc.
Of course I stuck it out, thanks both to the great support and the fact that if you can get past the pain points calibre is by far and away the best product out there. However it wasn't a "fun" process getting there during that first few weeks, and I wasted a huge number of hours that a few simple extra dropdowns/checkboxes would have solved.
When I first started adding books for the first week, I had no clue why or how titles and authors were swapped around, series info extracted etc. To find out I had to revist regular expressions just to get books into my library shocked me. Like an ever increasing high % of users out there I have a Kindle, not a Sony - so a metadata plugboard is essential, which can only be done by visiting the forums. I don't think like a librarian, so I don't agree with the default sorts which means learning about tweaks. I learnt the long, hard way that reading metadata from the file is not a smart thing to do.
I spent dozens of hours and went through several library attempts before I got a setup that did the basics of what I wanted. I was grumpy and annoyed at having to spend so much time searching through forums and experimenting. It all could have been solved by a couple of extra questions when I first started calibre.
What do people do if they are not motivated to go through the same process? They put series in their title fields. They put up with stuff sorting oddly, and metadata downloads not working for them. They use only a tiny fraction of what calibre can do.
If you don't want to add to the startup wizard, then the only alternative I can think of is something like a standalone "How do I" plugin. Something that gives a dumbed down user friendly front-end covering stuff like I have mentioned for the wizard. However since only a teeny % of users know what a plugin even is, it would have to be bundled with calibre. And for the users this is targeting to discover it, it would have to be on the main toolbar. And that would upset other/power users who think the toolbar has too many things on it already. Which is why I suggested it should be in the existing wizard.
Calibre is necessarily complex in the amount of settings it has to cater for all sorts of functions, devices and formats, so we can't just "remove" stuff, just because x% of users don't ever use it.
However for me the question is whether you even want to try to target users who don't care about any of that stuff, and just want to "put books on their Kindle". They don't know or care about the format wars, they only have one device to begin with, they just want to sort, categorise, search and send their books and possibly track ones they have read. Over a longer period of time they may get adventurous and start finding out about custom columns, yada, yada - but not during those crucial first few hours of trying out calibre to see if they will stick with it.
Now maybe you don't care about those users and suggest calibre is just not the product for them. Which is a perfectly valid approach, it gives you a (obviously smaller) user base that is slightly more technical or motivated and hence easier to support. In which case threads like this have an easy response.
Obviously for my own usage I have no need of some simplified setup nowadays, so I'm not going to get upset if everyone disagrees with me

. Certainly calibre has also moved on a lot since I started using it, the forums have been reorganised, stickies added, help file sections, obviously the plugin community I think I helped bring to life and so on. I do agree with the comments that say *once* you know what you are doing, calibre is very easy to use, and with the exception of the file system (yawn) no-one questions its flexibility. I would not have spent thousands of hours writing and supporting plugins/calibre if I didn't think calibre was worth the effort. But that doesn't mean I don't empathise with the OP about the first time experience