Matt, for the record I'm not against adding a skip element, I just want to understand why it's absolutely needed and why it would make cargo easier to use (I always tend to ensure there's only one way of doing things as much as possible).
I've checked your POM file and it seems you are already using a profile so I think the only thing you have to do is transform the activation section so that it's executed when a property doesn't exist. For example:
<activation>
<property>
<name>!maven.test.skip</name>
</property>
</activation>
That said I tested it quickly and couldn't make it to work. No idea why.
If you could make this work, would you be happy with it or do you still think it would be easier to users not to have to create a profile. The main downside I can see with the profile is that it takes more lines to write rather than a simple property to add.
BTW Cargo is NOT a testing plugin so skipping could make sense but so would it for any existing plugin. As a consequence a plugin skip property would make sense inside Maven's core. However I believe the chosen way so far for doing this are profiles... Hence my questions... 
Thanks
-Vincent
Hi Matt,
What advantage do you see over a profile triggered by the maven.test.skip property (this is the canonical way of doing it with m2 I believe)?
Thanks
-Vincent