Shooting down an airliner is a bit different to a terrorist bombing.
One was premeditated murder of soldiers by a terrorist group and the other an act of gross incompetence by an over aggressive commander combined with overreliance on technology.
The Vincennes captain was described as over aggressive by an officer serving on another ship in their battlegroup, whilst a USN admiral admitted the Vincenes was in Iranian waters at the time.
The Americans awarded the Vincennes captain a medal for his service in the Persian Gulf.
US never apologised for the action but did pay compensation in 1996 after the incident went to the International Court of Justice which ruled in Iran's favour.
There's no good or bad guys in the Iran-America saga. The Iranians may be a nasty dictatorial regime but then:
1. The USA supported the equally dictatorial Shah to 1979.
2. The USA supported Iraq in 1980-88 Iran-Iraq War including provision of satelite intelligence, turning a blind eye to Iraqi usage of chemical weapons and supporting loans from rest of Arab world and sales of weapons to Iraq.
The USN was also active against the Iranians in the 1980s whilst ignoring similar Iraqi actions in the so-called "Tanker War".
Indeed the Iraqis accidentally attacked a USN frigate with an Exocet missile.
3. The USA has gone out of its way to be anti-Iranian whenever it could. E.g. George W. Bush lumped Iran into "Axis of Evil" even though at the time Iran had nothing to do with terror attacks on USA (which were probably funded by US ally Saudi Arabia and initial training in camps provided by other US ally Pakistan).
Al Qaeda and Taliban are both Sunni whilst Iran is Shia, something that has escaped the Americans (but then they also accussed Hussein of supporting AQ which is also illogical as Hussein did not want Saudi sponsored religious extremists threatening his secular Ba'ath regime).
Bare in mind US and Iran were actually cooperating against Taliban up to that whole Axis of Evil speech as Iran has a vested interest in keeping Sunni extremists out of power.
4. The USA is supporting equally dictatorial Persian Gulf states to buld up massive armed forces whose main purpose is war against Iran.
This includes offensive systems such as long range strike aircraft and cruise missiles.
The Iranian military is effectively crippled whilst the Arabs now have larger and more well equipped forces than most European powers.
No wonder Iran was pursuing nuclear weapons – it's their only chance to create a deterrent against the Arabs, the Israelis and the Americans.
5. America and NATO has basically taken the Sunni side in the Shia-Sunni conflict.
This includes:
1. Tacit support of anti-Shia suppression in Saudi Arabia
2. Tacit support of suppression of Shia "Arab Spring" uprising in Bahrain.
3. Provision of air support to Sunni militants in Libya.
4. Supporting Sunni militia in Syria.
5. Supporting the extremely fundamentalised Pakistani military. Remember Pakistan's ISI created the Taliban and still support elements of it that act in pro-Pakistani interests.