Describe the project you are working on:
Projects that require me to create many animations, tracks, keys.

Describe the problem or limitation you are having in your project:
Creating animations, tracks and key is a very tedious process. Especially so when trying to animate not just one property of an object, but a few.

Describe how this feature / enhancement will help you overcome this problem or limitation:
If we had a record feature for the AnimationPlayer, I could hit "record" even prior to any animations existing, make a change to any object, hit pause or stop when I'm done, and only fine tune the timing and values if needed. If I made changes to multiple properties, (like scale, position, rotation, texture ... what have you) all those tracks and keys would be created for me. If there was no animation in the AnimationPlayer, it would automatically create a new one and give it a dummy name.

Show a mock up screenshots/video or a flow diagram explaining how your proposal will work:

Describe implementation detail for your proposal (in code), if possible:
I only got a C-- in the "How to turn your computer on and off" class. So I'm not quite on the level of C++ yet.

If this enhancement will not be used often, can it be worked around with a few lines of script?:
I suppose it would be used a lot, as it would make animating anything a whole lot faster and easier.

Is there a reason why this should be core and not an add-on in the asset library?:
It's another UX improvement (a rather substantial one this time) to the AnimationPlayer. I don't think you should need go to the asset library to make existing tools efficient to use.