Exclusions have been available for a long time in Maven, that's not the problem. Keep you current Maven version, it will do it's job well.
I think there is a confusion there. From the pom excerpt you wrote above, we can see that you import a pom (scope "import") which is often called a BOM (for Bill Of Material).
A BOM is imported in a <dependencyManagement> section (not showed above) and it's goal can be summed up by: "I define many different libraries, including their versions so that if you import me you can ommit to specify the version of the libraries you define, but you still have to explicitly define your direct dependencies".
By that, I mean that a BOM does not "force" you to use the libraries it defines: it only hints that in the case that you or your dependencies depends upon a specific library Z, then the version of Z will be forced to the one defined in the BOM".
So the BOM does not "forces" dependencies upon you so you cannot "exclude" any dependency where the BOM is defined. You have to find exactly where the dependency Z you want to exclude is defined in your own project and remove it there. It may also be brought as a transitive dependency in which case you have to use exclude it from the dependency you have specified using the <exclusions> / <exclusion> tags and the groupId / artifactId.
In conclusion: change your approach, you're not looking in the right place. And also use Maven dependency plugin which is your best friend to understand where your unwanted dependency comes from exactly ( mvn dependency:tree ).
I hope it helps
PS: you did not tell but do you have a multimodule project ?
<scope>import</scope>, even if we add exclusions, and add our dependency with a correct version ,it overrides the version.Hope i answered your question.this a case of transitive dependency Refer this issues.apache.org/jira/browse/MNG-5600