Capturing him and putting him on trail comes with certain problems that just killing him outright does not. Firstly you would have the precedent set by the PLO and Hezbollah, of an increased risk of the kidnapping of the civilians of whatever nation he was currently held in and of course holding them up in front of cameras demanding his release, then to only be killed because there would be absolutely no way the US would just hand him over - of course these sorts of actions already occur, as do the terrorist attacks that would likely increase if he were captured and brought back to the US or the Hague, but the hope is that by killing him you would decrease that risk. Secondly, if the trail were to have taken place within the US, bin Laden and his defence team would have been well within their rights to see any and all confidential information about how the US knows he's responsible for 9/11 and various other things associated with al-Qaeda that would be used against him and it is a distinct possibility that he and his defence team could subpoena any information regarding him that might have been omitted as evidence because it may harm national security, including ongoing operations, surveillance, informants, etc. Plus the result would really be the same, you'd just give him an extra 5 years or so.
An enemy in a foreign nation guilty of one attack against another nation and by all accounts planning more; if the nation in which he resides is either ignorant of his presence of unwilling to do anything about it, states are well within their rights to act in self defence.
An enemy in a foreign nation guilty of one attack against another nation and by all accounts planning more; if the nation in which he resides is either ignorant of his presence of unwilling to do anything about it, states are well within their rights to act in self defence.