@jan Dembowsky: Thank you for note, it was helpful. I appreciate it and understand point.
Unfortunately, I ask for admin access only when there is issue I can’t figure out from details and reports provided by latest version of plugin (like in this case, as I did not predict to wp_remote_get() fail to communicate with googleapis.com because server limitations/restrictions).
IMHO, it’s better to help user if I can, than to say “I can’t help”, even if that requires temporary dashboard access. There was only one user who denied to provide dashboard access (email support), and that is OK. But, I’ll consider that in the future.
These cases help me to improve plugin and try to make it available for all users/servers. Also, these cases makes better FAQ.
And, at the end, not all users are developers; sometime is faster to do homework by myself, than to spend ten days training user to master WordPress.
One more detail. As I often use premium plugins and themes, their support often request admin access, sometime even FTP access. And that is legit if I need to know what’s wrong with plugin/theme. So I though it’s Ok to do same for free plugins. But, will consider that in future.
Once more time, thank you for that note.