Uploading artifacts to JFrog Artifactory
this is actually by design of Artifactory. When you're uploading artifacts to Artifactory it will unpack it so you can browse the contents from the repository browser (as you indeed mentioned). 
When you're uploading a compressed archive (whether that is a zip or tar.gz or something else), Artifactory doesn't extract the subcomponents. The reason behind that is that zips (or any other archive) could contain many more subcomponents and those could contain many more subcomponents too (and so on). That would place a heavy burden on the Artifactory server by consuming, potentially, tons of resources.
We are using JFrog Artifactory and we keep jar files and tar.gz files into Artifactory. 
When we upload a jar file, in Artifactory we are able to expand and see the jar file contents like com -> mycomp -> app ....
When we upload a tar.gz file which contains jar file, we are able to expand the tar.gz file contents but we are not able to expand the jar file.
We are using Python to create tar.gz file.