the role of Britain's figurehead should be kept out of the hands of those who would actually want the job.
I have to agree with this. Imagine the populist vote? The winner of X Factor might be considered, or Beckham, or Holly Willoughby. 
I jest, but I'd rather have Her Maj than the likes of Tony Blair, Corbyn, Cameron, etc.
I do agree that we confer honour and privilege on far too many minor royals who may work the odd day in opening something, but for the best part swan around/holiday in a life of wealth and privilege. Harry and Megan come to mind, now that he is far removed from being heir to the crown. The royal family, imo, are a bit like a tree that needs quite a few branches lopping off.