Trying to loosen the direct influence of democratically elected officials from certain types of decisions isn't a bug, it's a feature.
Politicians run popularity contests, and often time politically popular positions aren't actually very good.
For example, taxes are universally unpopular, and so even though often times targeted taxes are actually the best answer, politicians won't because it may PERSONALLY cost them thier jobs.
It's similar to why we have an independent judiciary. Mob justice and the court of public opinion would rule otherwise. Insulating judges from elections is good.
You can actually see an unfortunate bleed over between justice and democracy in US counties with elected sheriffs. Arresting 'certain types' of people is more popular among the electorate than others, and I'll let you come to your own conclusions to what type of systemic issues that incentivized.
The BoC has a job, there are metrics to it's success, and when they aren't being met there are mechanics to shake it up.
I don't see these types of bodies existing at arm's reach from elected officials as a threat to democracy... I actually see them as protecting democracy from itself. It terrifies me that someone like Danielle Smith could ever have the official jurisdiction to direct a judge or central bank rates. We need adults who are prepared to make expert decisions in these positions who can make them, even when they're unpopular, without fear of losing their jobs.