Also, you have to remember that Kovid wrote Calibre to scratch an itch. He obviously doesn't have a complex workflow process to didn't see the need to add that in.
Also, the vast majority of users don't have a need for any complicated workflow processing. They process the books as they add them and really just use it to load their books onto their readers.
That's what I do. I normally only imports a few books at a time as I purchase or download them, fix the metadata and load them onto my reader. Books I've finished reading I tag as READ and that's about it. I don't need to do much conversions as my new PocketPro can read both mobi and epub and I generally only use my DR1000 for PDFs.
I think the majority of Calibre users do this too.
Yes, there are more sophisticated users and power users that want it to do a great deal more, but Kovid doesn't feel like it's necessary so doesn't add it in. Being open source, there are other users who have been adding various bits and pieces to do things they want.
If a sophisticated workflow process is important to you, and you've been programming for 30 years, the absolute best thing you can do is to start contributing to Calibre to make it even more powerful. I'm sure there are other users who would love that
Again, most users simply shouldn't be doing things that are overly complex as it just adds to their management burden. The simpler, the better!