@Protean I definitely understand your concerns, however a technocracy executed correctly is merely a democracy in which specialised politicians are replaced with specialised scientists or technicians. This includes specialists in law, doctors, humanitarians, physicists, mathematicians, etc.. A technocracy doesn't have to be oligarchic. Like I said, it can easily be a system in which politicians are replaced with people who have a deep understanding around the workings of society and the universe. A group of doctors, humanitarians, and law specialists will be vastly better when it comes to handling people and their needs on a large scale than a group of politicians, who are really only trained to debate. Mathematicians can work together to come up with accurate predictions for the direction of society, and can finance for an entire nation: much better than a group of people (as I said) only really trained to debate and campaign. These are just a few examples. I just don't see why anyone thought politics, the art of persuasion essentially, was the best way to go about running a country.
Yes our current system works, in which we employ large numbers of politicians to debate on the best direction for a country. However, it could be so much better. All we need to do is replace the politicians with specialists in their fields that, instead of debating, can work together to come up with the objectively superior decision for a nation. Right now it is very hit-or-miss, but it doesn't have to be.
It seems your main complaint is that certain people (such as those working in the arts or other non-scientific/non-specialist areas) will not be able to achieve power. Well, of course. I see no problem with that. What does an artist or an actor have to offer when it comes to technical analysis of the intricate workings of an entire society? What will they do? Even in our current system people need a lot of training in politics to be eligible for a leadership position. Just because someone doesn't get the chance to be involved in directly running the country doesn't mean they don't have a say. That is what voting is for. What I don't think you're seeing is that voting would still be a very present aspect of a technological society, so no one is barred from having a say.
The main difference with a technocracy is that instead of speculating and blindly steering the country, the leaders will make sure their moves are carefully calculated and thought through before putting any plan into action. The people in question are called specialists for a reason: they have invaluable insight into what effects certain decisions can have and in today's society they are often ignored. We see this in President Trump's recent withdrawal from the Paris Climate Accord, for example. Scientists have been ignored for too long and we are now seeing the negative effects of this. Look at climate change. Scientists have been predicting this would happen for about a century now, but it is only recently that they have been taken seriously. It is ridiculous, and could have been avoided if the scientists in question were given more power to begin with. Look at all the economic crashes predicted by professional analysts that happened because no action was taken.
It is simply better to have a group of dedicated specialists working on the ideal course for society. Yes, there is the possibility of a corrupt government. But, isn't there always? Measures can be taken to a void this. People need to stop condemning new ideas with the argument that it could go wrong. Of course it could go wrong. The first moon landing could have gone very wrong. That doesn't mean it wasn't a worthwhile pursuit. Any political system inevitably has the chance to run into a bad government. Stop using it as an argument, it is invalid.