Why shouldn't a newsreader be on £150k? I've been on film sets and it's unbelievable stressful, I can't imagine how bad it is on live TV. These people do that every day, at unsociable hours and on top of that they are the face of the channel. They are the spokesperson, they are the one that will be up on YouTube looking like an idiot if something goes wrong etc.
plenty of jobs are stressful and there are plenty of BBC news readers who aren't paid over £150k - like pretty much every regional newsreader
Some BBC news readers are on more like 500k, I think at that point why not just let them go to the competition? Unless you think all the other news readers the BBC employees are incompetent there would seem to be a big pool of potential replacements and no shortage of people willing to undertake that job.
Really they're paying for 'fame' not 'talent' and frankly, as a public sector broadcaster, they shouldn't need to. If someone gets a name for themselves reading the news and wants to demand big bucks for it then let them got to ITN and allow someone else to take their place.