I agree. Not every character needs to be an action hero. Some aren't suited to that role, either due to other responsibilities or having people they can depend on to do that for them. Even then, Peach has taken care of herself on some occasions, which is more than can be said for certain other characters.
For instance, there's a character in this MMO I play, FFXIV, named Minfillia (another blond girl with a penchant for pink, strangely enough). She's explicitly known as a diplomat, an activist, and a negotiator. This has naturally made her a target. Thus, she gets held hostage more than once in the game. Despite this, she never shows fear in the face of threats, never sells out her comrades, and always does the right thing. Yet people still criticize her for being "weak" because she doesn't know how to fight. Some of it is good-natured ribbing, sure, but there are always those who really believe she's nothing more than a burden. I don't get it. You don't see people criticizing the leader of the UN for not going out and killing ne'er-do-wells. That'd be ridiculous.