Sounds like a Fun project! Here is my input.
Beginner Players - I find that the beginning yoyo contributes a lot the persons interest. A solid yoyo with a slim and wide bearing included seems ideal.
Why do we throw - I throw because it feels more productive to do during my downtime than playing video games. I also like to do it while watching movies at home because I can’t sit still.
Durability - Plastic yoyos seem to be the most prone to this. Titanium is obviously the best bet or 7068 aluminum is supposed to be great but regular aluminum will maintain playablility through pretty much any abuse.
Space density - Not a huge problem with regular 1a. I stopped playing 4a primarily because of this though.
Other Problems - For me, I don’t yoyo in front of others and only a few of my friend know I yoyo. I know I shouldn’t care what others think, but I hang out with friends who trash talk a lot and yoyoing is an easy target and too obscure of a hobby to be taken seriously right now, by others. The only thing I could think of to solve this problem is to have a cool guy or gal take yoyoing into the mainstream.