I receive a lot of .ics invites for meetings. Because I work w/ collaborators in multiple different parts of the world, getting the time zone correct is essential (many of us are just using UTC, expecting that calendar software will properly convert this to local times).
Even when I get meeting times (e.g. 17:00 EDT) which are not that different (one hour!) from my own, they end up showing in my calendar as 17:00 CDT. This is a major problem!