Are we back to THIS again already? Thorhammer, have you not realized that you are the sole member of your minority that believes Sand Veil and Snow Cloak should be banned, or at least the only member who cares enough to keep bringing it up over and over again only to be rejected each time? I really don't get it. Do you think that if you ask enough, people will see the light and flock to your side? I don't think that's going to happen.
As for the actual issue at hand, Alphatron summarized it beautifully. Allow me to expand on this. There is only one Pokemon with Sand Veil (or Snow Cloak) we have ever had a problem with, and its name is Garchomp. We have another OU Pokemon with Sand Veil; its name is Gliscor. We have seen that Gliscor users prefer to use Poison Heal over Sand Veil. This means that Sand Veil is not inherently more powerful than Poison Heal. Therefore, since there is only one Pokemon who is problematic with Sand Veil, and another OU Pokemon is weaker with Sand Veil than with a different ability, we can conclude that the Pokemon is broken, not the ability. Your argument is like saying that Pressure is broken because Deoxys-A is uber.
About banning things that aren't broken: the only time it is acceptable to ban things that are not broken is if they provide nothing to the metagame. OHKO moves and evasion moves are not broken, but provide nothing to the metagame. Your proposed Sand Veil+Sand Stream ban DOES detract from the metagame (removes the possibility of using the extremely strong options of Garchomp and SR Gliscor on Sand teams), and thus is unacceptable. It is differentiated from Aldaron's Proposal because that was designed to ban something that WAS broken.