Is there some sort of fighting protocol that no longer allows us to engage our enemies with the most effective tools available?
Interestingly enough, under Clinton's watch, the Army published an updated Flame Weapons doctrinal manual which specifically reaffirms US policy and intent to use flame weapons during war (including napalm, flame throwers, incendiary launchers, etc.). The problem isn't that we won't use them. The problem is that we don't currently own any traditional flamethrowers and have destroyed most of our rusting/weeping stocks of napalm.
The old M202 Flash (a 4-barreled LAW-like WP rocket launcher) was a marginal solution during the 70's & 80's but suffered from minor flaws like the live warhead separating from the rocket booster about 2 meters in front of the muzzle... It had the range but needed some tweaks. Extremely Much Fun to shoot BTW.
Flamethrowers have always offended the sensibilities of some military leaders in much the same way as snipers. MTOE Snipers and their training programs were traditionally mothballed after every war until the advent of the standing all-volunteer force during the 70's.
Flamethrowers are bulky, heavy, offer limited range, and provide limited repeat fire. They are difficult to resupply. The operator must get very close (inside of 50 meters) to the enemy. The operator becomes a magnet for every enemy weapon on the field of battle while simultaneously requiring his buddies to provide good close-in rifle covering fire. This makes the flame gunner a lonely man (whom no one wants to be near) due to: 1) all the desperate enemy fire directed his way 2) the anticipated fireball when he and his weapon are finally hit.
Lastly, no one found with or near a flame thrower is likely to survive capture...People are rather opinionated about being burned alive.
For all that, the concept of flamethrowers and air-delivered napalm is being seriously re-looked after Afghanistan, where it was repeatedly called for in after-action-reports. We just don't have a capable modern version ready for deployment (yet).
We need to reinvent the "Alligator" of WWII Battle for Okinawa fame. Imagine an M1 Abrams towing an armored fuel trailer. Drive close to cave (with infantry support), shrug off RPGs and bullets, bring everyone to Jesus from 150 meters away...