I have some thoughts on the benefits of a simple "export all" function as opposed to a MySQL dump.
First, I think what I really want is a "backup and restore" function, rather than just "export all." Ideally this function would come in two flavors. One would backup your contact records, including their event registrations, constributions, memberships, relationships, etc. -- all of the stuff that's associated with a particular user. This way everything connected with a specific contact would show up in one place. The second "flavor" would backup all of your customizations, including custom fields, membership types, profiles, etc. -- all of the stuff you stick in apart from the contact-specific info. I'd suggest using a stable file fomat for this, such as CSV, so that this info could be backed up in one version of CiviCRM and restored in the current version.
Benefits:
1. This would make it easy and convenient to get the information out of CiviCRM for manipulation in other programs outside of CiviCRM.
2. A lot of the people who use CiviCRM are more comfortable working within the program than hacking around outside of it. If you don't know what you're doing, you can do a lot of harm by rooting around in your MySQL file. This is particularly true with a complex program like CiviCRM.
3. If somebody misses a few upgrades, this could provide a direct path for upgrading to the newest version, rather than having to install and uninstall each upgrade you've missed so you can run the database upgrade utility.