My question is here : Please convince me I have to make my propriety software open source.
You don't have to make it open source. I won't try to convince you that you need to. I will, on the other hand, try to convince you that you should open source it.
1. If your extensions are really nice, the community will use them, and will likely improve them for you. I've found this to be the case with the LDAP extension. 2. The community will find bugs in your software that your company hasn't noticed. This is especially useful for security. 3. It will garner respect and good will for your company in the community. 4. If you are not selling the software to others, it can honestly only benefit your company; internal software development is expensive, and this is a possibility to share that development cost with others inside and outside of your industry. Even if you are selling the software, you can switch to a support model. See Red Hat, and Sun Microsystems as examples (ignoring the fact that Sun is dying due to the Oracle merger). 5. These extensions may strengthen the MediaWiki enterprise community, which isn't a goal of the Wikimedia Foundation. The enterprise community needs some champions, and you can be one of them. Doing so makes it more likely that MediaWiki will be used in the enterprise, and will result in more enterprise features and extensions that will be useful for your company.
I look forward to having another enterprise member adding their contributions as open source. If you do release your extensions, please ask for commit access, and add them to MediaWiki's SVN.
Respectfully,
Ryan Lane