Kellogg's is a known cereal brand and is recognisable just by the 'K'. The use of interesting lower case font suggests informality, and that they are a relatable business. The fact that their main produce is cereal means they need to relate to a wide audience, e.g. men, women, and also children. The informality is therefore important as it shows a likeability to the potential cusomers.
The use of bold simple colour is used successfully as the viewer is not distracted by too much excessive and unnecessary decoration. Also as it is a logo that will be added to many designs of cereal boxes it's important it stands out and is recognisable by itself.