Patents are entirely to do with licensing, nothing else. The rise of the patent, within the computer industy specifically, reflects a culture change within that industry. About as many software patents were granted in the US just last year as in the whole of the 1980s. Has the use of personal computers changed much in that year compared to the 1980s? I think not.
Up until the mid 90s, the computer industry was predominantly product based. Software was thought to be well enough protected by copyright law not to need anything else. And besides, software isn't even meant to be patentable is it? Computer companies played their cards close to their chest until they released a system, after which any innovations were bound to be copied. The entire IBM PC was cloned FFS! That would never happen now as IBM would have patented every part it could, not through expectation of success, but just in case it was. Would the design then have been licensed to other manufacturers? Probably not.
Now we are seeing what ARM got right, and Acorn only understood too late to act before imploding: A huge upsurge in the importance of IPR. This isn't a huge suprise as it's basically the way the winners were operating from the start. If Digital Research had cooperated with IBM on the licensing of DR DOS, Microsoft wouldn't have dominated with MS DOS. And if Apple hadn't protected the look of its GUI by suing DR, or Xerox had thought of suing Apple sooner, everyone might have been running GEM desktops on IBM compatibles (Actually that reminds me, AMS: The Atari ST was booting a GUI from ROM before the Archimedes).
So in summary: in addition to what others have said here, comparing numbers of patents are not an indication of relative innovation because they have only dominated the industry since shortly before Acorn's demise. Go and see how many computer related patents you can find filed before 2000.
It is also interesting to see how many are even remotely innovative. Read a few.