Uta Utane (or Defoko)
Again a follow-up from my article about UTAU, this is about the default voice you'll get when installing the package. Her name is Uta Utane (Utane Uta, 唄音ウタ) or Defoko (デフォ子), but that's something I won't be calling her since it's not nice to call someone the Default Child. When searching for her on YouTube you'll have to use the term though.
As you might hear, Uta has a robotic voice. This is not because the voice recordings where altered using some kind of software. This is because her voice is 100% synthetic. It has been made with AquesTalk, software distributed by the company Aquest Com, If you have the software, Uta's voice is called female-1. The creator of UTAU got permission to create a voicebank using this software.
Having a robotic voice, Uta isn't a voice for the beginners. It is fairly hard to make Uta sound good. Making a good quality song using Defoko requires quite some knowledge about UTAU. Because of this, Uta isn't very much used in the overseas community. She is, however, fairly popular.
This is the first time i've seen the second video, and it's very beautiful and sad at the same time...
Like you said, not many people can bring out their charms easily, and it also depends on the style of music they are singing in XD
I think this goes for all voices, both UTAU and Vocaloid. You need to get a feel for their voices.