There are no specific examples I can think of right now. But I have dealt with problems where the _force_ on an object was a function of time (not necessarily increasing). In such a case, given the mass, with SymPy's integration abilities, we could be able to find the velocity/position vector as a function of time.
It may not be as common as forward dynamics, but some users may want to have that functionality - of specifying vectorial functions of time, with boundary cases, and getting the motion parameters calculated.