This has nothing to do with simplicity. Any other apriori selected sequence, such as first 200 binary digits of pi, would be just as unlikely.

Yes, under the hypothesis that the coin is fair and has been flipped fairly all sequences are equally unlikely. But under the hypothesis that someone is lying to us or has been messing with the coin simple sequences are more likely. So (via Bayes) if we hear of a simple sequence we will think it's more likely to have be artificially created than if we hear of a complicated one.