As has been noted, all modern western aircraft are certified to land up to MTOW in an emergency (i.e. in excess of MLW).
We had a 763 in Britannia a couple of Summers ago which landed 40,000kg (about 88,000lbs) overweight operating a MAN
flight, after smoke in the cabin after departure.
Nice landing by the skipper, and after the overweight landing inspection which revealed no damage, and a fix for the smoke issue the aircraft was on her way again 2 hours later, courtesy of a standby crew comprising yours truly
I have also landed a 757-200 overweight (can't dump the fuel on those birds, as with 737s and A320s).
Another factor to consider is that most a/c with fuel dump will do so from the center (centre) tank only, like the 767-300, and getting rid of all this will not reduce your weight to MLW in most cases anyway! Bit of a pointless exercise IMO.
Remember also that dumping fuel, even when desireable, might well be prohibited, due to turbulence, thunderstorms, or any fire (engine, cargo hold...). If you were on fire of course, and want to dump fuel before landing to reduce to MLW, you need your head examined.
I used to love the smell of Jet-A in the morning...