It may be more secure on a computer that is used by more than one person, but that computer is not mine. Personally, I prefer an OS to do what I want it to, rather than it telling me what to do. I keep hoping that someday that Linux will become more attune to my preferences, but it is becoming increasingly clear that is a vain hope.
Well you can bypass the passwords in linux but its not advisable.
After all windows has dozens of security issues because it gives administration rights by default.
In windows anyone can be administrator and screw up the system but in linux there are barriers.
Just because you dont like the extra passwords doesnt mean the whole spectrum of linux has to change just for you.
If you like insecurity, vulnerability and a system that anyone can hack into just use Windows.
Sorry if this sounds like a nasty reply here, but its a common thing I see windows users ask and sometimes force is needed to get a point across.
I mean its just a password after all and is only one minor step in the grand scheme of things.
Plus in Kubuntu its only one password, in some distros you need both a admin password and a user password.
To be honest with you passwords should have been a standard in windows too, its no wonder why XP had so many holes.
Windows 7 is better as it uses UAC but even that can be circumvented.
Here is a PCworld article covering some of the key reasons why linux is more secure:
http://www.pcworld.com/article/202452/why_linux_is_more_secure_than_windows.html
There is another "little" quirk that you might be able to help with...Default Programs. The options that can be set are quite limited, but I do have Opera set as the default browser, yet when I select a link from an email it opens in Firefox. Also, I can't remember exactly when, but sometimes a page is opened in Rekong. It seems that Kubuntu doesn't understand exactly what the definition of "Default" is. Is there some way that I can teach it?
Actually you can teach it, using the system settings and going into "default applications"
For more complex file associations there is the file associations section.