There are cases where you have the opportunity, as a developer, to enforce stricter security features and protections on a software, though they could very well be managed at an environmental level (ie, the operating system would take care of it).

Where would you say you draw the line, and what elements do you factor in your decision?

Concrete Examples

User Management is the OS's responsibility

Not exactly meant as a security feature, but in a similar case Google Chrome used to not allow separate profiles. The invoked reason (though it now supports multiple profiles for a same OS user) used to be that user management was the operating system's responsibility.

Disabling Web-Form Fields

A recurrent request I see addressed online is to have auto-completion be disabled on form fields. Auto-completion didn't exist in old browsers, and was a welcome feature at the time it was introduced for people who needed to fill in forms often. But it also brought in some security concerns, and so some browsers started to implement, on top of the (obviously needed) setting in their own preference/customization panel, an autocomplete attribute for form or input fields. And this has now been introduced into the upcoming HTML5 standard. For browsers that do not listen to this attribute, strange hacks^* are offered, like generating unique IDs and names for fields to avoid them from being suggested in future forms (which comes with another herd of issues, like polluting your local auto-fill cache and not preventing a password from being stored in it, but instead probably duplicating its occurences).

In this particular case, and others, I'd argue that this is a user setting and that it's the user's desire and the user's responsibility to enable or disable auto-fill (by disabling the feature altogether). And if it is based on an internal policy and security requirement in a corporate environment, then substitute the user for the administrator in the above.

I assume it could be counter-argued that the user may want to access non-critical applications (or sites) with this handy feature enabled, and critical applications with this feature disabled. But then I'd think that's what security zones are for (in some browsers), or the sign that you need a more secure (and dedicated) environment / account to use these applications.

^{* I obviously don't deny the ingeniosity of the people who were forced to find workarounds, just the necessity of said workarounds.}

Questions

That was a tad long-winded, so I guess my questions are:

• Would you in general consider it to be the application's (hence, the developer's) responsiblity?
• Where do you draw the line, if not in the "general" case?