As Lapo rightfully explain, providing a button there for creating a new
event is way to prominently and might divert users of the intended click
on a cell behavior to create an event.
New event will be also accessible from the hamburger icon on the left of
the header-bar and Ctrl-N key shortcut.
Also as Lapo suggestion Today button fall better on the header bar than
between the navigation buttons.
Georges Basile Stavracas Neto