I think the point you highlight Junkyard is valid, certainly for extreme wealth.
However, i think for someone who earns £200,000 a year, which IMO doesn't fit in with your extreme above, to see £25000 of that £50000 over the £150000 threshold just lost to tax, seems rather extreme to me.
Who is anyone to say that this person hasn't worked damned hard for that money? There total tax and national insurance bill would be in the region of £80,000.
Now, where do you stop / start tax brackets is another question, and one I don't have an answer for.