As i said above we used to use only wet runway performance data as standard. In fact there was no dry performance data available. The use of said performance was authorized by the relevant authority so it was of course legal to use it that way.
Most probably it was an issue of size since we had to have the performance data for all european airports that a 737 can use on board and we used paper performance tables back then. You can only carry so much documentation in that cramped cockpit.
With our EFBs now of course that is not a problem and we use dry performance data on dry or damp runway and wet performance on damp and wet runway (damp is pilots discretion).