You, diego, et al. seem to have difficulty coming to terms with the author. It is clear from the article that by "frighteningly ambitious" the author means problems people currently have which seem insane to take on. They are problems people have because the author has indicated that he has them or has discussed with others who have them. Search and email are insane to take on because if you succeed with search, you are decimating a company with market cap in the hundreds of billions; succeeding in email means disrupting one of the original Internet protocols which virtually everyone uses. Thus, these are frighteningly ambitious.

You instead see "frighteningly ambitious" and assume your own term which is in the realm of science fiction (cyborgs, personal robots, &c.). Robotics, incidentally, may be a frighteningly ambitious endeavor but only if you are considering something like autonomously scraping and repainting ships or actuation in camera pills: personal (autonomous) robotics won't happen in the near future (see iRobot Corp).

So, assuming the author's definition of "frighteningly ambitious", search and email are important because they are problems people have now. If search weren't a problem, Union Square wouldn't have funded DuckDuckGo, and more to the point, DuckDuckGo wouldn't be growing. (I also have the exact problems the author describes with Google -- for the past 2 years I've had a problem with Google.) If it hasn't been shouted by Fred Wilson and Paul Graham enough: they have pain from dealing with email. They would throw their money at you if you offered a way to make email less painful. Maybe instead of spending two hours every day with email they could spend one hour with new/email and they could have a spare hour a day with their kids -- how valuable is an extra 14 whole days a year to these guys? How many people hate spending so much time on email who have means? Probably enough to make it worth investigating the problem. For what its worth, I'm frugal as Franklin and I would actually pay for email (i.e I wouldn't accept any common free email service because they aren't even worth $0.00 to me for a variety of reasons).