and again...about FUEL DUMP...most planes don't have it and don't need it by regulation. offhand I would say that the 747, 777, 787 have it....some, not all 767 have it.
the DC8 had it, and Air Canada bought DC9's with it...though no one else has it on the DC9 and it was turned off later on the ones equipped with it.
Boeing even put out a chart that I have, but can't upload, of Boeing planes that did have fuel dump.
I think the L1011 and DC10 had it too.
There are some cases which for PERFORMANCE issues require the ability to dump fuel...and this performance is for engine(s) out go arounds. And while bubbers and others are right, you can GENERALLY come back to the runways you just took off from, there are specific situations , mainly with extremely long range planes loaded with huge amounts of fuel, that require dumping.
fuel dumping (while helpful) is not SOLELY for protecting the structure of the plane on landing.