While there is increased complexity on top of all the software thats being built today, I reckon the focus on speed (and shipping to prod) over quality has also led to the increasing number of bugs. The mindset shift from shipping quality products (not just software) to shipping something that is good enough has been the mantra of management in recent years. When business schools and tech leaders prioritize the idea that we need to be more agile and every sprint needs to be a production release, these are the results we get.