Ethereum didn't just shorten block times, it uses a variant of the GHOST algorithm, which as originally proposed for Bitcoin as a way to speed up blocks and increase throughput while maintaining good decentralization and security.
Thanks for understanding me. Unfortunately my original comment seems to have been massively downvoted by uninformed HN readers.
Sure, uncle blocks help increase the weight of the chain but are also wasted blobs of data forever taking up space on the blockchain. They serve no value other than to make the PoW weighting heavier.