Probably startups that don't want to outsource their design and user experience to a giant corporation that genuinely does not care about their users on an individual basis.

The idea-refining sounds invaluable, it really seems unfair to burden that with outsourced ui/ux.

Want to be clear, though, that Google Ventures tries to keep pretty separate from Google. Also, the better GV's portfolio companies do, the better GV does. My impression is that the design team actually cares.