There are currently as much as 4 ways to simultaneously adjust all tracks' heights in the Track view:
A) Press Ctrl+Up/Down allow keys
B) Right-click on the Time ruler and drag the mouse up/down
C) Hit Ctrl+A (to select all tracks), then drag up/down the bottom edge of one of the track strips while holding down Shift
D) Drag up/down the bottom edge of one of non-active tracks (only when Auto Track Zoom is enabled)
But, I must say NONE of these is quite as fast/efficient/convenient as the method my other daw (which I'm very likely to ditch soon) offers. It allows users to assign (predefined) track heights to keyboard shortcuts, like this:
You might think this isn't very different from method A above. But imagin your tracks currently have very different heights. With method A, you'd have to hit Ctrl+Up allow key several times before you start hitting Ctrl+Down arrow key to achieve a desired height.
Hope it makes sense.