How important are the two lower cowls with the weatherstripping at the bottom of the windshield. Passenger side one has virtually none of the weatherstripping left. Drivers side weatherstripping is cracked in several places. Is it an actual problem if water goes down the windshield there or does it just drain out somewhere with no harm done? Wondering if it's worth $100 or $150 to replace them since I don't know the downsides of just leaving them alone. Thanks.

 

There are usually some electrical connections just under that edge and it is better to prevent water from dripping on those connections .
Sometimes you can use door weatherstripping foam to help there.

 

Windshield wiper motor, bulkhead wiring and connectors come to mind.