We could include a tweening of tool parameters. E.g. Two points in one frame, and other two points in other frame, so we can draw a line on each frame interpolating those points. Anyway a path layer (#814) with keyframes and interpolation curves would be more powerful (and non-destructive).
IMO Photoshop is a pain in the brain to animate in, it's unstable (when starting to animate), unhandy and lacks fundamental features, like moving more than one graphic at once (!) when using timeline instead of frame-based animation, which is necessary for tweening. So if Aseprite got a tweening feature, like adjusting parameters over several frames as described above, eg. position and rotation – the angels would sing.
The Path Layer function is in the Aseprite 1.4 roadmap (in the future). In the middle, you can give a shot to a recent script to make path movement/rotation of an object through a path: PathAnimator (code in one Lua file: path_animator.lua, and mini gif tutorials are included)
Github code (source code, path_animator_tool.lua is the main file to run the tool dialog)
An example of how someone can play with it: