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Thats a good point.
I would counter though, that Infield singles are more valuable than walks and Ichiro's performance has never suffered with runners on base.
With a runner on 2B and infield singe up the middle or the right advances the runner. With a runner on 3B any infield single that isn't perfectly placed in front of the 3B will advance the runner.
Infield singles are less valuable than normal singles, but more valuable than walks.