I mean why wouldn't a simulator want to have dynamic weather? Even ignoring rain, tracks vary in temps based on time of day and usage and the grip levels change. It should be a good thing where racing isn't just hotlap simulator and you need to react to changes in grip levels (or moisture).
Speaking from my own experience, the addition of rain to iRacing has been an incredible thing as it changes everything. Every lap you're seeking the limit as the track wets or dries with real reward/consequence from getting it right or wrong. It makes the experience more enjoyable.
Even in dry, having a track evolve over a 3 hour endurance stint where the lap times get faster or slower based on track temps and tyre wear which is interesting to have happen.