On package-install x package-install-selected-packages

[Gabriel]

On package.el, the 'package-install' calls
'package--archives-initialize' to initialize the archive contents, but
'package-install-selected-packages' does not calls it, relying on users
to initialize the archive contents by themselves. I could not find any
documentation about this difference. Should we modify
'package-install-selected-packages' to call
'package--archives-initialize' ? Or add some flag to control this
behavior ? Or update the documents to account for these subtle
differences ?

Also, 'package-install-selected-packages' always asks for a confirmation
to install or not the packages. Can we add an option to skip this
confirmation ?