Put in the time to do it right or don't do it at all. Don't just put in a bad scene so that you can advertise romanceable companions.
Why is it a bad scene? We only have the companion conversations at the moment, not even any of the companion sex scenes.
For me, the party fling makes sense story-wise. These people have been implanted with an alien tadpole against their will, have been through hell and back (literally), have been thrown together into an extraordinary situation, and haven't had a moment's rest from all the fighting. Finally, something goes right for them, they save a bunch of people, and get to unwind and forget their problems just for a night in a nice atmosphere. Well OF COURSE some of them are horny. :P Sex is, after all, a natural human behaviour, the party is a good excuse to explore that as part of the story, and each of the companions' scenes reveals something about them as well.