Of course we could simply graph the point (1.26 m, 4.2 s), which represents our best estimate for the point, but actually what we have is not a point! The position could reasonably be anywhere between 1.22 m and 1.30 m, and the time could reasonably be anywhere between 4.0 s and 4.4 s. Your "data point" is actually a "data rectangle"!
of indicating the precision of a data point using a rectangle, it is
common practice to use "error bars" to indicate precision. (I suppose
coloring in all those big rectangles doesn't seem like a good use of
time to physicists, and it would certainly get confusing with
closely-packed points!) Error bars are simple to draw, and most
software packages designed for scientific graphing, such as Graphical
AnalysisTM and Science
WorkshopTM, will do them for you quite easily.