I don't expect wet weather in AMS, but for their next game I think Reiza really should work to have dynamic weather in all tracks, imo that's one of the standards of modern racing sims.
Just wander, if it's missing because Reiza are using the defult G-Motor "wet track" system on the "dynamic track" feature.
Rain? Id never worry about using it as its difficult enough to drive in the dry. Seems about as important as driver arms, better graphics etc! Dont worry about that stuff and just focus on improving the FFB!!