Thanks for the feedback and the progression of this is interesting. Originally we were not able to override Ctrl+p and Ctrl+n since this meant print and new tab respectively in standard web browsers. Note that RStudio is also designed to work over the web. We then switched editors and use Ace, another open source project, and got Ctrl+p to be used for brace/parentheses matching in the source editor. However for the console, Ace is not integrated, but we do have plans to eventually do this which will give us more freedom.
Finally, we also eventually plan to allow customization of keyboard shortcuts in which you could then set this as you wish. Unfortunately, this isn't available now, but I'll chalk up another request on our feature suggestion list.