The Senate has to have the agreement of its members to do so. Harry Reid was not able stop McConnell / GOP from keeping the Senate in pro-forma session while Reid was majority leader - because he had no such power. Just as McConnell has now such power now.
Obama declared, under his own power, that the Senate was in fact in recess while in pro-forma session and made recess appointments. This was a massive scandal widely discussed here and one of the most worst and most frightening power grabs in history. McConnell / GOP Senators filed suit and it went to all the way to Supreme Court which slapped him down 9-0 - the appointments were null and void, the Senate, and only the Senate, gets to decide when it is in recess or in session, and all of the actions of his illegal appointees were declared null and void.
But since that SC ruling any recess long enough for recess appointments has to be approved by the House anyway.
But, yeah, Members won’t do it. I suspect an agreement was reached on judicial appointments to make the issue go away.
And I believe Trump, as an outsider without a list of Party sycophants to turn to, couldn’t fill many positions advantageously.