If you look at it from a logical point of view , as has already been stated, the SW on the ATIS would be the ten minute average. whereas the wind passed to pilots would be the two minute or Instant wind (if asked for by the pilot or deemed necessary by the ATCO)
.
If one adopted the "only if it varies significantly principal "
I would have to firstly check the actual reading ,
THEN, compare it to the wind speed and direction given on the ATIS ,
THEN, compare the two readings ,
THEN, establish if the difference is considered significant
THEN ,if it is ,Pass it to the A/c along with take off clearance.
At the moment dare I say, the convention is
Cleared take off ( rwy if necessary) surface wind XXX degrees YY kts.
I believe the degrees and kts can be dropped
One simple action against against five.
As for passing the QNH if it had changed I have to
and the TEMP if it went through 25C then again I would.