I find not having the option really annoying when you're in a situation (e.g. relaxing) where you want to navigate with one hand. The right hand can drive the mouse and has easy access to pgup/down, arrows and backspace, but reaching for alt forces you to do crazy finger gymnastic, or use your second hand.

For me that's not the biggest Chrome deal-breaker anyway (besides privacy), as Chrome doesn't support stack-like behavior for switching tabs with ctrl-tab.

Not sure if there's a PC/Linux equivalent but Chrome (and other browsers I believe) on Mac also supports two finger swipe on the trackpad to go back/forward which works well in one-hand navigation flow.

(I also use BetterTouchTool to add similarly simple gestures for open-in-tab, close-tab, switch between tabs, and go-to-top/bottom)