Even if the graphics are not impressive on a technical level, the art style is extremely appealing to look at, even more so than any AAA game I've played in the past 5 years. It looks like a world that I want to explore, and learn about.
But neko is pronounced 'neh-ko' not 'neeko', so the portmanteau doesn't really work.
Really I think it's just called Trico because that was the codename (denoting Ico 3), like how SOTC was codenamed Nico (Ni = two in Japanese). It probably stuck because of the happy accident of 'Tori'.