If you start upgrading you might encounter some duplicated license files build errors (which were discussed in several issues here). Gradle Android plugin 0.9.1 brings a new solution to this:
It's now possible to include a file when there's a conflict during packaging:
I'm not convinced it's better or worse than excluding them. Excluding them actually makes sense since the JAR is essentially a binary and you're typically removing license text files.
A useful heads up from @ollide.
I think this is much better than simply excluding them.