Proportion of GDP spent on research is not a 'meaningless' number. The EU spent a great deal of time trying to (unsuccessfully) urging its member states to push their total spending up to 3%. They've since realized that no single metric can adequately measure a nation's capacity to innovate in science - but this measure is still part of a basket of metrics that it's perfectly reasonable to use to examine a country's commitment to science.
To be clear - there's little evidence that spending a lot of money science will get you a Google or a Genentech, but on the other hand, a fair bit of evidence that spending nothing will make it extremely unlikely. ie science spending is necessary but not sufficient.
A list is only as strong as its weakest link. -- Don Knuth