Why, after decades of redesign and enhancement, does it still rain inside B737? For as long as I can remember, seats 1A/1B suffer from rain during acceleration/takeoff as the condensation pours down from the heavens, (well, the overhead panel where the reading lights, gaspers, etc. are).  I guess it was, at most, a minor inconvenience until pax started carrying more consumer electronics in their hands. Now it can be costly.

Obviously, I can fix the issue myself by avoiding those seats, but sometimes they're the only extra-legroom seats left, and I'm tall. I try to remember to keep my electronics pocketed until after takeoff, but it's so boring sitting there while 188 other pax try to stuff their inflated bags into straining lockers, and I forget.

I can understand that this rotation rain, or similar aggravation, might happen on a new aircraft design; something undetected until mass operations and not safety-critical anyway, but how is this still happening on an aircraft that first flew decades ago and has had so many enhancements?  I can't be the only one who has had a Seattle soaking, so why has this, possibly costly, annoyance not been fixed?  It can't be that difficult/expensive to cure, surely?
I've never heard of this on a 737. The last rows in a DC-9/MD-80 series is where I seen this the most.

The simplest solution is for the flight crew to set the cabin temperature control to not be full cold on a humid day. Just a little heat will cut down on the condensation being developed while sitting at the gate.

Here's an interesting article on moisture in the airplane, though it is not specific to the gasper vent rain. 

http://www.boeing.com/commercial/aeromagazine/aero_05/m/m01/index.html

Some larger aircraft have dehumidifiers, but as the Boeing article states


  Dehumidification systems (ground-based or onboard) are effective at removing moisture but are not cost effective.