I think I’d prefer it if the symbols to be prefixed with a namespace required a :: instead of having to prefix every external call with ::.

I.e. I would prefer

    (require 'externalpackage)
    (define-namespace thispackage-
    (defvar ::foo "yow")               ; foo is explicitly local, and
                                       ; since it is short, an extra
                                       ; "::" does not make much
                                       ; difference
    (externalpackage-frobnicate ::foo) ; frobnicate is external
    )

to this, which is how the package works currently:

    (require 'externalpackage)
    (define-namespace thispackage-
    (defvar foo "yow")                 ; Some things like defvar
                                       ; magically don’t need ::
    (::externalpackage-frobnicate foo) ; Ugly, and I need to do this
                                       ; for *every* non-local symbol,
                                       ; making them even longer!
    )

So, because RMS doesn't like CL packages we get something that is clearly inferior to CL packages and implemented in a very hacky way (a macro you wrap around all the forms in a given .el file).

Sometimes, when you avoid solutions for political reasons, you end up with something worse for political reasons. <sigh> Sometimes the world is frustrating.