Hello,
I need host permissions for each of the translator services my addon supports, so theoretically, I could replace with a list of 7+ domains, one of each translation page.
However, some translators are using also other domains, for example google translate also loads data from "gstatic.com". Plus if they ever change it in the future, I would have to ask for a new host permission, which would force each user to approve the new permission!

So using permission for all pages solved this issue, even though for a cost of big and dangerous permission :(.
Note that originally, this addon was developed only for Thunderbird, where permission to "access to all pages" is not as big issue since people don't open pages there :).

In any case, as with all of my many addon, I'm doing my best to protect users data and privacy: https://github.com/fastaddons/privacy_policy

I hope this helps :)
Have a nice weekend!

Best Regards,
Juraj Mäsiar