Why does Ubuntu delete useful apps from the repositories?

I used to use pyrenamer a lot. Havent needed to batch rename files for a while, but today I do. I went to install pyrenamer via the usual command, and its not found. Did a bit of researching and found that Ubuntu has deleted it.

What was the point of deleting this software? Even if it hasnt been developed over the years, even if it was abandoned, why get rid of it? Why not just add it to a new category of abandoned apps, and allow people to install it?

http://www.webupd8.org/2016/03/quickly-batch-rename-files-in-linux.html