Why add-ons have no .po file ?
I don’t wanna translate in code file.
Sometimes, no , Very usually to change original code for translating.
It’s really awful to replace translated source code file .
Please learn from Wordpress.
WordPress is used all over the world, in countries where English is not the main language. The strings in the WordPress plugins need to be coded in a special way so that can be easily translated into other languages. As a developer, you may not be able to provide localizations for all your users; however, a translator can successfully localize the theme without needing to modify the source code itself.
For blender foundation must solve this issue,
1 .don’t let developer re-code ,
2. don’t translate in source code file.
How to solve this issue? 
If supply po file , many Chinese blender users will translate all of them, developer don’t care about it . it’s our job.
Right now, We will do it and done most of addons. but the issue that we have to re-translate it while updated . Most translator don’t wanna translate again for all of it. Nobody do that.
So, please supply po file.
Thanks so much !