I had one wisdom tooth which was giving me trouble - had broken the surface and got infected, painful, etc.
The other 2 were giving no trouble at all (4th had come through fine after an extraction in front of it)
On my dentist's recommendation I had all 3 out under GA, having had to arrange parents to come hundreds of miles to look after baby DS.
When I got to the hospital I was given a form to sign which detailed the fact that there could be complications like nerve damage. But... since parents had travelled so far, etc, I just signed and didn't feel it was a good time to think through what I really wanted.
They damaged a nerve under one of the ones which had never given me a moment's trouble in my life. The bottom right side of my jaw felt halfway to numb for several years (like when a local anasthetic is wearing off) and then tingly for several more years.
DS is now 20, and the sensation in that part of my mouth is still 'different' from the rest.
So... if they can't give a better reason than 'just in case' I would strongly advise not taking the risk. If they can explain why the risks of leaving them are worse than the risks of pulling them out, then that's different of course.