hi the reason that the top ones are angled is to do with tyre contact with cornering loads
in a car with parrelel bones and therefore the mounting points = to the hub top and bottom ball joints, when a car corners there is a lateral force which will try and compress that side of the suspension, now if we had a car that would corner flat the this would be acceptable but in reality this would need to be a solid axle with no suspension.
with the angled top bone this allows the top of the wheel to prescribe an arc as the suspension moves in relation to the cars lateral cornering forces.
in the former situation the tyre will lift reducing the contact patch available thus less grip and by association less cornering ability. in the second situation the suspension movement allows the tyre contact patch to remain constant ( to a point) as the body rolls thus allowing the grip and cornering ability that we love.
and we haven't even considered tyre pressures and sidewall flex
Now this is a very simplistic explanation of a very complex issue that many more learned people than me have studied and fought with for years and probably will continue to do so
there are many tomes on the subject but staniforths race and rally car source book explains it well
sorry to be so long winded and I hope it makes some sense
all the best Gary