Having been on both sides of the mike, including as ATC in the UK, I would suggest any pilot who doesn't want to "maintain visual" learn how to enter the hold until the skies are absoultely void of other traffic...
I'm sure more complete (and accurate) information will come out in the months ahead.
It's not that a crew would never take a "maintain visual" clearance, but rather that there might have been a good reason for them to not take this one.
It's 0100 (airport of origin time), it's a mountainous area, they see lights that appear to be the 747, they see a lot of lights out there, they are cleaning up and working the go around, it's 0100 at the airport of origin (yep, I said that twice).
I am certain this crew has taken many "maintain visual..." clearances and will continue to do so. Like you, I would be interested to hear more about what is reported in the news media. I am happy to wait for an official statement.