Decades of meticulous planning and they couldn't give their teams a day off on Christmas? Of course it could be that consensus was this beats any other kind of activity that day in which case fair enough. :-)
It's going to be awesome for us to watch but I feel for all the folks that worked on this.
The Webb self-assembly is absolutely where the scary bits lurk.
There is a handy list on wikipedia: https://en.wikipedia.org/wiki/List_of_objects_at_Lagrange_po...
Your intuition is quite right, there is way less satellites parked around L2 than in low earth orbit for example.
But that doesn't really pose too big of a challenges in itself. It is of course far, both distance wise and energetically.
The main complication often mentioned is if something is wrong with the telescope it makes it very unlikely that a crew can visit it to fix it. The way for example how they repaired Hubble is unlikely to happen with Webb.
Now, both Ariane 5 and Atlas 5 are extremely reliable, mature rockets.
Webb will be monitored and operated by NASA in Maryland.
https://en.m.wikipedia.org/wiki/James_Webb_Space_Telescope#T...
https://en.m.wikipedia.org/wiki/Space_Telescope_Science_Inst...
Let's just hope it all goes well, this is one of the most complex space endeavors we've ever tried, and if it fails it will have many negative long term implications.
I also hope all goes well. Cheers.
Some of the grunts might be disappointed but having worked on way less important things that were launched on holidays, I can guarantee anyone significantly involved in the project is just happy to see it get off the ground no matter what day. You have a good window for launch, you take it