Why Madagascar
Different people and different organizations act for different reasons. Madagascar can mean a lot of things for a lot of people. Feel free to add below your messages, as text, images or movies, for any category of potential users!
Individuals
Graduate student in small research group
Academic researcher with strong theoretical background
Professional researcher
Project manager
Corporations
Disorganized company
Tightly-run company with managers that never did professional programming
Academic research group or small company
Start-up company
Geophysical services company
Computer hardware company
Geophysical acquisition systems company
Why not another open-source package?
Most of the reasons above apply to any open-source package as well. Madagascar is not the only open-source geophysical package, but it is the only one to provide all the components of a shared research environment as described at the beginning of the Overview. Also, it has an active, diverse community of developers (as opposed to a single owner and a mass of passive users) and its current and future freedom is guaranteed by the GNU General Public License (2 or higher).
Why not rewrite Madagascar in-house?
The Project Cost Calculator on Madagascar's Open Hub (formerly Ohloh) metrics page shows the estimated cost for a project of this size. You are getting all this for free!