Main problem this equipment (amongst others) is not its technology (simple and sturdy) but its certification specification dating back roughly to the early jet age in the last millenium.
Today's long-haul operations are led a a far more stringent environment than in those (golden, some of the posters will surely say
) days.
We can be certain that the people who had established and validated the pitot's specification had never thought about flights at FL 350+, at -50° (and even below) and during several hours.
Time is up to revisit this type of "old" specs to ensure that they are still applicable in today operations.