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I'm not sure I fully understand why RAID10 is better than RAID5. Reading the RAID wikipedia article, they seem to imply that a typical RAID10 setup uses n*2 disks, where each block of data is written to two drives.

But how does that help in the case of drive failure? If a drive fails, then as size increases won't the exposure to a URE also increase? Is it better than RAID5?

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When a drive in a RAID10 array dies, then the data on that drive is still directly available on a drive that's not protected by redundancy, and the other half of the data is still protected. Rebuilding the array requires reading a single drive without error. Rebuilding a RAID5 requires reading n-1 drives and computing parity without error.

Indeed. Reed Solomon coding (maybe only available in system software, not disk hardware) gives you efficiently balanced striping+redundancy

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