Of statistics and genomes

Higher organisms have more genes and larger genomes than simple organisms. This statement sounds almost too trivial to ask the question: why? But there are at least two different answers. Either there is an inherent necessity to increase genome size when more complexity is required or genome size increases because of other reasons that then enable complexity to 'latch on'. Recently, an article by Lynch and Conery, which used arguments of evolutionary population dynamics, proposed that low population size leads to larger genomes. This then provides the opportunity to generate more complex organisms