Agreed - MUST HAVE!!
Why oh why are we still having to ask Microsoft to show shared mailboxes and calendars on mobile devices. In my case - a windows 10 phone!!
I strongly agree - same problem for me.
We want limited visibility (subject / location) to be the default to make booking meetings more efficient and encourage openness. The user can always mark an item as private in exceptional circumstances.
An example of efficiency improvement is the case of booking a meeting for, say, 10 people and 4 appear busy. If only Free / Busy is shown then a minimum of 4 calls / emails are required and it may end with rescheduling starting the process all over again for all 10. Whereas if some information is available on what the conflicts are and hence the likelihood of flexibility, a more educated judgement can be made and an appropriate time found far more quickly.