How to automatically activate XML-RPC publishing for new blogs

Part of the selling proposition for my blogging network is that users can blog using the native wordpress apps for smartphones and tablets. Majority of my user base are not techies and might find some difficulty configuring XML-RPC that these apps need to work.

Is there any way XML-RPC publishing can be automatically activated as new blogs are being set up?

If this is done, is there any security risk attached to it?

Thank you in advance for your help.