Regarding Air Strikes, I just finished the originial Splinter Cell game, there were no air strikes. Not sure about Pandora Tomorow because I can't remember, I'll be playing it again this week and will check. Chaos Theory had one but it was part of the story line and made sense as to why they were needed, to destroy the plane and keep the secrets and technology from the enemy. There were no air stirkes in Conviction other than the helicopter missles to destroy the generators.
The problem I have with the air strikes in Blacklist is that I don't think Sam should be able to call them nor do I think Sam should need to call them. Once again, this game should be based on Stealth. In the situation we saw in the demo Sam should have been able to get around that truck by shooting the guy on the gun, creating a diversion, using a hand grenade to blow up the truck or the best solution would be not to even let the enemy know he was there, which should be the primary focus of every single mission.
The bottom line is that I don't want to be FORCED to use the air strike yet I'm sure that we will be and that will be extremely dissapointing.