Asking, or perhaps insisting others pay their fair share is hardly calling for NATO disbandment. Nor is it an unreasonable ask by Trump. But from a negotiating perspective there has to be a consequence or else it's meaningless words.
Agreed: however, if that means Article 5 of the Washington Treaty now carries a caveat (though you could argue it is already there with Article 3), drawing the resolve for acting in collective defence further into doubt will only stoke the fear and mistrust of the 'eastern allies' and make the whole thing a dead letter anyway.