Every wedding hall I know has space to accommodate a bed in the yichud room (Its not a phone booth.).
Most people are just not interested in bringing one in. People usually realize that after the party they get to go home to a new apartment where no one knows they are there and no one is knocking on the door to take your picture. Things can be enjoyed in appropriate order and things can wait for the best relaxed moment available.
As the OP already states, consummation in the yichud room is not required. I do not think there are Poskim who ask that a bed should be there.
Why shouldn't we be "machmir"??
1) There is no reason to be. It doesn't achieve a better Halachic situation.
2) Even if you do wish to press that it would be somehow "better" Halachically. The fact is that "derech eretz kadmah la'Torah"
Since decorum, relaxation, the feelings of the couple to wish to be normal and let the evening flow in an appropriate manner etc. is part of the normal and good "way of the world", then such constitutes "derech eretz". This goal or perception of normal behavior trumps the pursuit of "what if chumrah".
BTW, anyone could bring the bed in. There is no law against it. Take a look... there are no takers. But if you want to throw a wedding with such a setup, who is stopping you?