I agree CRI difference is negligible and most can't tell the difference. But CRI is just one pro/con.Not much price difference these days between low and high CRI. In fact, just quickly browsing prices at Mouser there's no difference between CRI 70 and CRI 90 LEDs in the same family. The CRI 90 ones put out about 20% less light though, so for any given output the LEDs will cost about 20% more. However, at this point the emitters themselves comprise only a small fraction of the total cost of LED lighting. The cost difference then between lower and higher CRI is often close to negligible. In any case, high CRI LEDs aren't "much more rare and expensive".
100 CRI isn't needed for any outdoor lighting applications. In fact, it really isn't needed for anything but demanding color matching use. Most people can't even tell the difference between CRI 90 and CRI 100. Anyway, for outdoor lighting CRI 80 is more than good enough. Or even go with CRI 90 if you're that concerned. It won't increase the cost by much, if at all.