My $0.02:
Any attempt to redesign the UI could, with minimal additional effort, be used to create a second UI possibly sharing some base classes, such that both the current UI and the new one are available depending how you start calibre, or alternatively, depending on a configuration setting.
It is a COMMON COMPLAINT (well, relatively common enough to stick in the mind), for people to say "oh, calibre is the worst ever, because its UI sucks". Many of those people complain that it isn't Apple-conformant enough, others crave Windows Metro everything, and that's just the tip of the iceberg. Usually such people come in rude, and find a reflection of their own attitude in peoples' responses, at which point they storm off, claim they'll write a competitor program that does ebooks better, and then gosh, wow, amazing how said competitor never materializes.
It's nevertheless true that there is merit to the complaint, inasmuch as there are people who would prefer a different interface. It would be nice if they had that option, which might be billed as a "power users interface" and a "give it to me simply" interface with likely reduced functionality in order to simplify common use cases.
@openartist, I will second what theducks said. Thank you for posting this in a friendly, open manner that doesn't dismiss the hard work that was put into the existing UI.
Moreover, I encourage you to do just what I said above (and which I think I've mentioned a time or two in the past). Teach calibre an alternative user interface that can cater to the needs of people who find calibre's abundance of widgets and options to be too confusing. I think there is a lot of room for healthy growth in calibre along these lines, but the key will be to let people choose.
I think there's a good chance that Kovid would accept such an option.
...
An even more ambitious project, perhaps, would be to design a new plugin subsystem for skinning calibre, allowing users to trivially install plugins (although probably not trivially write them
) that change calibre's appearance, whether that is simply generating the interface with a different layout or redesigning the toolbars, or what have you.
To a limited extent this is already what things like Preferences -> Look & Feel -> User interface layout -> wide/narrow, or the layout toggle for the cover grid, do. Just... bigger.