Do that many people hate the Outlook calendar? I like it (maybe a bit less in OWA, but honestly it's pretty much the same). Appointments show up, meeting rooms are pre-populated, I can see when other people are busy when writing an invite and move the meeting (or reconsider if it needs to happen at all). Oh, and when people email me invites they show up in my calendar, which doesn't work nearly as well when your calendar can't see your mailbox. Google Calendar is also fine (if a bit less comfortable).

It's not a task list, but that's a problem for Trello or something, not a calendar. (Outlook has a task list, but I'm not a big fan of it). Anything that doesn't involve meeting with other people or me being in a different location for a period of time doesn't go in a calendar. If I need to block to do deep work, I can just put a big block on the calendar and go to the task list to figure out what I need to do (and the task list probably has some sort of prioritization, anyway).

We need better productivity apps, but the calendar seems like a solved problem (unless I'm desperately out of touch and everyone hates Outlook/GCal).