By default, Treemap view fills the view pane. You can use the View -> Magnify command
(Cmd+1) (Cmd +=) to make the view bigger, in which case the view pane can be scrolled to allow any part of the treemap to be viewed.
Given this, it’s tempting to say “can’t the view just initialise so titles don’t wrap?”. However, people’s choice of titles vary wildly - many use very long titles so I suspect there might need to be a limit.
Regardless (i.e. as at v7.3.1), you can enlarge treemap view so titles - at least those not of excessive length, can be viewed in full.
Edit: cited wrong shortcut, now correct.