So why no save a few tons of fuel in the centre tank, and use it for the final descent and landing? All you have to do is turn off the centre tank pumps at say five tons remaining, and turn them back on at TOD.
For this particular incident maybe that would have worked. However running both or all 4 engines from a single tank from the same source would seem to be a negative step and against the design philosophy.
What happened is one of those accidents that aircraft designers/airlines rather than the pilots need to learn from, something that has been rare since the late 1970s.