As I have posted previously the development of Q2studio has had a huge impact on my, and I am sure others, ability to start processing and analysing data that has previously been under the remit of informaticians and statisticians.
However, us Q2 studio users are now getting greedy. There is a constant stream of new plugins e.g Picrust2, and some current tools e.g. meta_data_tabulate that at the moment are not available in Q2studio. Are there any plans to update the studio package at some point (I realise its only an alpha release) to add new features like those above or allow plugin developers to incorporate new tools into Q2studio.
There are two aspects to that question - features, and plugins. I'll start with plugins. The good news is you can extend deployments of QIIME 2 Studio with plugins, just the same as with q2cli and the Artifact API. You will just need to activate whichever environment you typically use the Studio in, then follow the plugin author's installation instructions. Plugins are designed to be interface agnostic, and a la carte.
The second half of your question has to do with "features" - I suspect you and I have different definitions of those features (my impression of your post is that you are lumping "plugin functionality" under that definition, but please let me know if I misread!). The most feature-complete interface at present is q2cli --- we support things like Artifact validation, metadata validation, and a handful of other "features" there (that is, functionality that doesn't have anything to do with a particular plugin). The Studio has fallen a bit behind with regards to feature parity, and we don't have an ETA at present for when that might get updated. With that said, one of the exciting things to me about QIIME 2 is you don't have to limit yourself to only one interface --- you can mix-and-match to suit your needs! So, if there is functionality like Artifact validation that isn't in the Studio, you can always jump over to q2cli for a minute, then back into the Studio. Better yet, if there is missing functionality, we would love for you to contribute a patch, if possible!
Anyway, if you get stuck installing a particular plugin, please let us know!