The idea here is creating tentative events in one's own calendar, not tentatively accepting someone else's events. This is to prevent overbooking oneself. It's a simple feature and I'd personally use it a lot.
NO - you clearly have never worked in a fortune 500 enterprise with tens of thousands of employees with oversight (Director of OPs) for their thousands of employees' email....
You have never managed a massive Exchange Network. (a pain in the butt)
Tentative acceptance is a feature that was oft underutilized.
I MAYBE will be there - but dont accept me for other shit, especially when I have an AE scheduling me?