Not everything that is ethical is painless, or fair, nor will it make everyone happy.
Attempting to address old inequities by tilting the playing field has, as shown, the potential to cause friction between different minorities...but leaving things exactly as they are and waiting for a more ethical system to evolve on its own is likely to take until the next Ice Age...
The inertia inherent in the relationsip between superordinates and subordinates is substantial, and just waving a Constitutional Amendment around and chanting 'everybody is equal' won't get it.
Without a system along the lines of AA, how long do weu think it would have taken for there to be minority alumni at Harvard, so that their children could start to enjoy the perks of being a 'legacy'?
Some of the vestiges of the old system had to be dismanteld, and unfortunatley it got 'fixed' in a clumsy and imperfect manner.
One of the negative consequences was when African Americans adapted to a power vacuum, and started discriminating against other minorities...AA is not the only place where this happened, but it created a double set of gate-keepers...one white, and one black, making it harder for other minorities to move up in society though access to higher education, jobs, etc.