This uses the
\addvbuffer service routine from the
verbatimbox package to condition the
\includegraphics with, in this MWE, an extra 12pt above and 8pt below the second image.
without using the figure environment
this is the default spacing. But with \verb|\addvbuffer|,
the gap above and below the image can be tailored
While one could redefine
\includegraphics, I would strongly recommend against it. If adding the text were too onerous for each image, one could define a
\myincludegraphics to do this, without tampering with the original.