> Yes, its already there and quite organized in directories.
So you do understand the general concept of a library. Then you also understand the limitations of directories and how much work goes in maintaining this system.
> Now ebook readers came along and pressed those hierarchical data flat, with long waiting times, because it needs to index first.
I don't think Ebook-readers started this. ITunes had this first I think, or whatever app ITunes copied from back then.
> grep and find works quite well for most work loads and are fast, why not enhance (or fork) them to support ebook formats?
Doesn't solve the problem. Grep and find don't give a useful interface for elaborated tasks. They also don't support metadata which are not supported by a fileformat, meaning "external" metadata.
> And at the same time omit very useful information that normal file managers show. (File creation/write/access time, size, full file name, etc.)
Depends on the application, and the user. Not all of those information are useful for everyone. Calibre for example has good support for filemanagers. Each entry has a link to open the folder with the ebooks. The whole library is saved as a folder-hierachy with metadate extrated into seperate files. The Database-View is just an additional layer.
> As I said, with long indexing times. I had ~50000 books on a ebook reader once and that broke it. Just because there are files stored, that should not slow down the system or even make it completely unusable.
Indexing is a neccessary tradeoff for gaining power. The alternative would be to constantly scan all files, making every single task slower. grep and find have their price too.
> But very few ebook applications and handheld readers have the same resources to implement a similarly powerful library functionality. Instead they have half backed solutions that make finding and organizing the library more difficult then if they would have simply used a standard file manager and grep/find/...
Oh yeah, I guess grep on an eReader would be a real pleasure to use...
> IMO an application that lets you just open epubs and other ebook formats and render them correctly just like so many pdf viewer do, without any half assed library functionality duck taped on to it, is highly sought after.
Those applications exist. Calibre even comes with one out of the box. Not their fault if you just start the library and not the reader.