The apps that have mono icons in the indicators are specially cased in the code directly. Ubuntu One (and other apps) is not. I also think the icons you provide here need to ship in the ubuntu-mono-{light,dark} themes respectively, rather than in ubuntuone-client or ubuntuone-control-panel. We shouldn't be installing icons into other themes like that.
The apps that have mono icons in the indicators are specially cased in the code directly. Ubuntu One (and other apps) is not. I also think the icons you provide here need to ship in the ubuntu- mono-{light, dark} themes respectively, rather than in ubuntuone-client or ubuntuone- control- panel. We shouldn't be installing icons into other themes like that.