I think its more along the lines that Sony (moreso than MS) just developed what they wanted and never checked to see if it was patented until it was ready for release.
Nintendo on the other hand decided what they wanted and then checked all the patents that come even close to what they want to design, then designs around them as not to impose on other patents, then patents their own carefully researched design. Thats why everytimg Nintendo does something, they are either really late to the table and/or they do it in some round about way that makes no sense to anyone as there are other more known ways to already do what they are doing.