why maildir?

Can someone please explain why cpanel is pushing to change mail format from mbox to maildir??

Having each email in its own file is an awful idea.
A large user could have thousands of mail in his mailbox this presents some problems

1. Hard drive block size.
Its usually 64KB, means that even if the email is only 1kb, it takes up 64kb of space which cannot be used by other files, this wastes space. (10,000 1kb emails will take up 640MB of space, instead of 10MB if it was mbox!!!) i dont know about others but some of my customers mailbox files are 100mb+ which would be a big problem with maildir.

2. inodes.
Each file requires one inode, there are only so many inodes on a file system, wasting them in this way and you wont be able to save any new files to the drive.

3. speed.
In just about every situation imaginable, its preferable to have one big file then thousands of small ones, especially for backups and when copying/moving files from one device to another, especially over network, if you have ever FTP'd thousands of small files you will know what i mean.

4. disk seeking.
when reading files the hdd takes time to seek to the location of the file on the physical drive.
using maildir will make the drive slower and reduce its lifespan


now.. whos crazy idea was this? and what are the benefits?