Hello,
with slower accelerations, it'd become much harder to make winner, so it'd require to lower run speed as well, and then the whole gameplay balance will be threw off and everything would need to be retuned...

Moreover, the actual average speed of the acceleration is relatively in par with the real tennis ; it probably could be even a bit more high, but as you said the precision & risk should be then reworked.
So all that is work for TEM2 & TE4..!
