Am well aware that user input can be 'sanitized' to prevent 'oops' errors or any 'funny business', but still contend that there are many who wear the hat of Moodle Admin that are not also the true server administrator. I'm not sure I would consider someone who uses tools like cPanel to be considered true server administrators, either. Now if there were some admin only tool Moodle provided that did show size of and space remaining for at least moodledata location then no problem ... the Moodle Admin hat as information needed to make a semi-informed decision.
Obviously, anything could be argued .... small site vs large site ... X vs Y, etc..
Nothing prevents anyone from posting suggested fixes/improvment suggestions in Tracker. ;)
'spirit of sharing', Ken