Just to add...if we get the ability to have the tempo track function like automation, we'll also need the ability to vertically zoom in on the tempo track in order to make small changes. Without vertical zoom, minor changes would be near impossible.
Here's a link to a detailed forum post in the Meldoyne thread where I detail what I feel are the current weaknesses in S1's tempo track:
End conclusion in all this, there's 3 things that would really expand the tempo track functionality and workflow (from jpettit in that thread):
1) Data Zoom so you can zoom to see minor tempo changes (Like the peaks and valleys shown).
2) Change from bar to line to represent the tempo. With this new process the tempo map look excessively busy.
3) Free form line draw to simulate tempo mapping if you will.
EDIT 6/10/2018: So adding to my old answer as I've spent more time thinking about this...
1. Allow users to quickly pop out or maximize the tempo view for fast vertical zooming of resolution
2. Allow for freehand drawing of tempos using the paint tool
3. Allow for drawing of parabolas, sines, triangles, etc. using those line tools
4. Create an option for ramping up/down or jumping between two given tempo points
5. Bonus points for bezier curves, as just having two points with a bendable curve would be much cleaner and easier to edit
I think if the "behind the scenes" resolution remained at 1/64 notes with the current 3 decimal places, no one would care as that's not the issue. It's really about improving drawing/editing.