Ever since MyBB had a facility to create database backups, we have had questions on why there wasn’t a similar facility to import backups. The following reasons were taken into account while designing this feature:
If a user somehow managed to get into an administrative account with the correct permissions, they could potentially revert your forum to an earlier state, or run arbitrary SQL queries on your database.
The use of an externally-installed database administration application reduces the chances that a malicious user can perform these actions on your database through MyBB.
We are developing a bulletin board system. We are focused on bringing you the features that will help run your bulletin board. Although database backup and restore are important tools, they are not used on a day-to-day basis in your forum’s administration. The backup function has more frequent use than the restore anyway. Our development resources are limited and we do not have the capacity to develop a fully-featured database administration program into the bulletin board software.
Third-party database administration programs are specifically developed for the purpose of managing your database. Their features are more robust than what we can provide. Just like how we concentrate on discussion board features, their development teams concentrate on what their product is: database administration.
In order to keep the MyBB package a reasonable size, we have to be conscious of what features are implemented. It is a waste of both physical and human resources to have a large package (clunky to install and update) with a steep learning curve (difficulty of usage).
Dedicated database administration solutions have the ability to incorporate more useful administrative features because that is their focus.
In the hypothetical case where an import facility is indeed incorporated into MyBB, the requirement of using it is a working version of MyBB. Let’s say you just upgraded to MyBB 1.4, but you do not like it. Your database backup is 30MB. You start restoring it via the MyBB 1.4 Admin CP, but the restore times out part way. Your database is now half MyBB 1.2.x and half MyBB 1.4.x and neither version will operate correctly. You will need to resort to a third-party database administration program anyway to complete the process of reverting. A doctor can’t heal himself if he is unconscious.
A third-party database administration program does not depend on anything you are operating on. Even if an operation times out, this does not affect the program, you will be able to use the same program to correct the problem.
I hope this sheds some light on the rationale behind not including a database import feature.