the press has gotten too big for their britches. a symbiotic relationship has grown up between the press corps and the white house in which the press get access and the white house gets favorable coverage, from the best spin possible* to having peeps that are willing to forego journalistic standards to be mouthpieces for strategically and anonymously leaked information that benefits the administration's agenda.
and after years and years of this they've forgotten that there's no law that gives them access. they have access because they're used by the administration. they benefit the administration so they get access.
in the case of trump they've spent 1+ years saying bad things about him and trying to spin him in the worst possible light. they've exaggerated, made up shit, speculated, and printed all kinds of anonymous information to try to hurt him. and they're still doing it. and now they want access
he doesn't have to give it to them. I guess they could try to sue or something, but afaik the only thing they're entitled to is information that's guaranteed under public records laws that apply to the president and governmental actions. good luck with that. even the most liberal judges would be like "oh, first amendment blah blah blah but there's no guarantee to access."
if they're not serving their usual rah-rah function why the fuck does he need them?