Oh, somebody else likes BCIs! I skipped your essay on my first pass, since the abstract suggested it would just be, as you say, "a shameless excuse for introducing some ideas in physics". :)
As Shirazi already pointed out, your argument against our living in a simulation assumes that physics works the same way in the real and the simulated universe. I am puzzled by your response that you only assume that "the simulators use quantum bits". When you get to numbers on page 5, to find limits on the complexity of simulations attainable by computers of various sizes, you necessarily introduce objects and scales from our universe: Earth, stars, black holes and the cosmological horizon. The relevance of those scales to a universe governed by different laws is unknowable. As for "Wovon man nicht sprechen kann, darüber muss man schweigen", I find it works best before you've written a whole paper about the unspeakable. :D
Maybe we can agree that yours is a fair assumption for the kind of "ancestor simulation" discussed by Bostrom, but not in the general case, which some of us find even more interesting.
Unfortunately I see no possibility of such compromise regarding your statement that "So far nobody has come up with an effective idea for why humans should go into space.". The ultimate argument has been made many times by many people: as long as we are all sitting in one basket, it only takes one extinction level event to wipe out humanity. A less severe (and more common) kind of event bad enough to destroy our technological infrastructure would suffice to permanently tie us to Earth, with its limited future lifetime. Self-sufficient colonies in the solar system would extend our potential future to the sun's lifetime (modulo some really unfortunate cosmic incident); interstellar travel to the galaxy's.
More near-term arguments involve the exploitation of natural resources and moving industrial activity harmful to living things out of the biosphere. Much can be done by machines, but when you reach a level of complexity where continuous human supervision and decision making are required, telepresence only works over short distances. The round trip to moon, L4 and L5 is more than two seconds at light speed, and the asteroid belt is minutes away; way too much to get anything done in real time.
Moving on, you opine that "One might in fact be hard pressed to think of many serious national or world problems that we have actually solved over the last half century." This kind of despondence is common enough, but is it really grounded in fact? The last half century began in 1965. I could hit you with plenty of statistics on things like world poverty, hunger, education, democratization and emancipation of women now and then, but I'm lazy, so I'll just point you to Gapminder World where you can pick and choose indicators, pull back the slider below the graph to 1965, and then set the visualization playing. See how things move up and to the right? The world of 2015 is a lot better than the world of 1965, and not just because we now have this intertube thing with all it entails.
Regarding your "observation that those who rise up the ladder of power to do the steering, within government, business and other socio-economic structures, have over the last decades been of an increasingly inferior nature", I would need to know what sample you are basing that on. I do no question that human institutions are generally less than impressive, but have they ever been particularly good? We remember a few exceptions from the past because they were, well, exceptional - and even then, one should ask how much is myth and how much is reality. Last year, the United States commemorated the 50th anniversary of John F. Kennedy's assassination. Less than three years marked by escalation in Vietnam, Bay of Pigs debacle and near-death experience over Soviet missiles on Cuba are now "Camelot" in the imagination of a public mostly unborn at the time. On closer inspection, "Camelot" turns out to be a myth single-handedly invented by Jacqueline Kennedy after the fact (and presumably before she found out about Mimi Alford). In fairness, JFK did give a good speech in Berlin, and he did authorize the continuation of project Apollo (born under Eisenhower's watch) so that's something...
