In some approaches to Special Relativity the theory is motivated talking about the Michelson-Morley experiment and how this relates to the postulate that the speed of light is the same in every inertial reference frame. Once someone has this postulate, it is quite simple to argue tha time cannot be absolute. This leads then to a new viewpoint about space and time and everything follows.
Another approach, about which I ask here is much more geometrical and has a nicer mathematical structure already prepared to generalize to General Relativity. The motivation for this geometrical viewpoint is just to consider Special Relativity as Galilean Relativity with absolute time hypothesis relaxed. In that case we derive the Lorentz transformations quite easily and everything follows.
Although this motivates the mathematical structure, I still cannot understand how to motivate this quite drastic step on dropping absolute time. I mean, absolute time is something quite natural, and it is so natural to think about it that Galileo, Newton and others before Einstein always did so.
The Michelson-Morley experiment motivates this step, but it's quite messy: we first postulate the constancy of the speed of light. Then with a thought experiment we show that simultaneous events in one reference frame are not in general simultaneous in another frame. Then we argue that time shouldn't be absolute at all.
Now is there another way to motivate dropping absolute time assumption? I mean, what is the real situations that shows us that we need to drop the absolute time assumption and how can we intuitively see that dropping it will solve the problems at hand?