Great to hear you find the plugin useful - there has been a number of great changes to the reports in the latest version (thanks to contributions from other members of the community) so make sure you are using the most recent version. Then feel free to add a new issue in the github tracker with any further improvements you think would be good. Please make sure you are very specific in the issue (screenshots help a lot).
I don't think we will ever see the attendance activity part of the "core" Moodle release, but the plugins architecture that Moodle provides makes it very easy for organisations to add to their installation. I also try to make sure that the plugin is tested before any new major Moodle release comes out so that people can upgrade as soon as they would like to.