I don't think there was anything to see. The Americans had to use facial reconstruction software to ID Osama originally, which means his face was pretty much missing. Bury the body at sea, get rid of the damn thing. The last thing we need is a spot for a martyr.
Al Qaeda is a splinter cell, but Osama was the one who moved resources around. While this doesn't end the individual threat of each cell that currently is out there, it does remove their ability to shift resources from plan A to plan B. In other words, this hurts Al Qaeda 5 years down the road. We don't know how extensive this is going to be yet, but it does hurt their ability to cause terror.
I haven't heard that they began this by torturing (don't use euphemisms) someone. According to Obama, they got actionable intelligence several months ago and worked to confirm it. Unlike Zare, I think this is necessary: if they had gone into a compound and found, say, some legitimate but eccentric Muslim with money and power in the Pakistani government, it could have been terrible for US-Pakistan relations.
As an aside, a lot of analysts are suggesting that, combined with the Arab Spring movement, this will signify the end of Al Qaeda as a force. The Arab Spring seems to have legitimized the feelings Al Qaeda harnessed to recruit; all of a sudden, supporting the Tunisians, Egyptians, and others doesn't seem like such a big deal after all.
This is a victory for the Obama foreign policy, absolutely; ballots, not bullets, have won the day in the Arab world. The death of Osama bin Laden, hiding in a compound, only proves that. Change is made by popular waves, not by extremism.