Aikido has a strong philosophical foundation and thus appeals to people looking for an MA that satisfies them ethically/philosophically as well as physically. For someone looking for a more physically 'robust' art regardless of ethical considerations then Aikido may appear hippyish. Krav Maga springs to mind, it seems to be the MA of choice for true 'street effectiveness' by many people because its techniques are brutal. However, while brutality may strengthen confidence in one's ability to protect themselves, sometimes it goes beyond lawful reasonable force and doesn't take into consideration the ethical ramifications of using such excessive force. As martial artists we have a duty to use our art and skills responsibly and wherever possible, humanely.
Looking for a physically robust martial art are we? Having sampled at first hand the waza of some senior uchi deshi of O Sensei I can state categorically my body ached from head to toe.Some of the longer serving guys in the U.K. also know what I mean about robust practice. Cheers, Joe.