sudo is available on all linux distros, so using that as an argument against Ubuntu (or any other distro) is fallacious. Heck, it is available on OSX.
In terms of asking for the password too often, that is configurable for sudo.
The superuser password is not the same as the user password, the sudo password usually is, but does not have to be. Also, it is important to note that you can configure sudo to only allow certain root access processes to be allowed, and you can restrict which users can use sudo at all.
I would actually say that the continual attempt to make linux a popular (say even default) desktop OS is flawed. No, I don't say that windows, or OSX are not (as easily) open to options on desktops as linux. This is actually their strength. With the exception of win 8, any user can sit down at a Mac, or a windows box and just use it.
Linux is not, and IMHO should not, be trying for the masses, as all it will do, should it achieve this, is inherit the flaws of windows/OSX.
Furthermore, installing linux on an apple computer seems like an odd choice, since OSX is a desktop put ontop of BSD which like linux is based on unix. If you can do it on linux, you can do it on BSD is (for the most part) a true statement. They are not binary compatible from my understanding, but the strength of linux is that you can compile from sources.