Glad this came up @the-future. I asked @timcliff (vote for him as a witness!) a question along these lines 2 days ago. How to get a new tag. He answered: "if you use a tag that has never been used before, as soon as you make .01 SBD on the post - then it will become a new tag" - he qualified that by saying that it may not even need the 0.01SBD. Further, he said: it will not show up in the list though unless it makes a significant amount.
So, creating a new tag for your theme which has longevity ... you need to garner support from likeminded people. To the best of my knowledge it is only @sirwinchester who has his own tag! (let's all post under his tag!! - Joke)
At the same time, one of my bugbears on steemit is when I see a new recipe clogging up one of my go-to channels - 'news'. What was the author even thinking - or were they using a channel which has a lucrative history in the hope of snagging an opportunistic vote?
The tag/topic range is far too small and there is a disproportion of steemit-related tags.
Your initiative is more than overdue - Thank you!
I hope that rather than inventing whacky tags like 'ball-bearingphotosynthesis' which will just get github angry, that the good steemianistas out there will write under a tag which they will use and use and others will use and use.
Thank you for this great initiative! Namaste.