170 GB is insane. Publishers should really get punished for making larger than average deliveries. Most of that size usage usually comes from poor optimization.
They’re typically optimizing for fidelity and performance ahead of install size. Multiple LODs can balloon an install size quite quickly, but they’ll give you better bang for your buck in other areas, and storage space is a concern that dissipates more in time, as you upgrade to newer machines.
I have seen this theory floated a few times. The problem is that reading uncompressed files from disk can often be slower than reading less data and decompressing it on the fly efficiently. Would be interesting to see actual studies of this for common game data.