Updating Confluence to use Axis2 would provide several advantages. (Currently Confluence is using Axis-1.2.1 which is becoming a bit dated)

• Axis2 is faster. I haven't done any bench marking but it's suppose to be an order of magnitude or two faster according to docs and comments.
• Development is ongoing
• The documentation is better
• The .NET compatibility is better.
• The code bindings it generates are easier to work with than Axis 1.x (personally I like the XMLBeans bindings you can now optionally generate)
• Axis2 has better memory management

The above points mean it will generally be more productive to develop using Axis2 both in terms of providing and consuming web services.

Having more robust Confluence web services and tools for both providing and consuming external content will encouraging plugin devel.