Yes, Tanenbaum was right. But it is a hard sell, even today, people just don't seem to get it.
Bluntly: if it isn't secure and correct it shouldn't be used. But companies seem to prefer insecure, incorrect but fast software because they are in competition with other parties and the ones that want to do things right get killed in the market.
Are there other obvious tradeoffs, in addition to speed, to these more secure OS systems vs status quo?