Secondly JSOW is hugely different to a JDAM-ER. Apart from the sensor options in JSOW it is a stealthy weapon. Now why would anyone go to the both of designing a stealthy glide bomb/dispenser if it wasn't necessary? Well I guess Mr Weasel of 1962 on the DefenceTalk webpage knows more about ATG tactics than USAF/USN and the Raytheon/Hughes Aircraft company.
I bothered to read the Raytheon JSOW datasheet
here and I would like to point out something. In the last sentence of the 2nd paragraph...
JSOW’s low radar cross section and infrared signature are key stealth features and ensure a high probability of survival en route to heavily
defended targets.
While "stealth features" are mentioned, that is not the same thing as claiming the JSOW is stealthy. A 500lb bomb is naturally going to have a smaller RCS than an aircraft unless the aircraft itself is LO. Same situation exists for the IR signature. The JSOW being a glide weapon is unpowered, therefore the IR signature would mostly come from air friction on the winglets and would therefore be lower than that of a powered (and larger) aircraft, excepting again possible LO aircraft.
There is no mention of a significant difference between the JSOW and JDAM or other bomber in terms of IR signature or RCS. Therefore it would be premature to claim there is without other sources.
The datasheet does mention that the muntion is designed to be survivable in a highly defended environment. What seems to be overlooked, again, is context.
Take a look at the "opening day" of an air campaign conducted by the USAF. A large portion of the initial efforts are directed against IADS via general strikes at C4ISR assets or dedicated SEAD/DEAD missions. The only real reasons why a defender would possibly engage a piece of incoming ordnance is that
1. It is the only potential target the defender has detected...
2. It is the only potential target in the defender's range
3. The ordnance is directed against the defender
#'s 1 & 2 are part and parcel of why stand-off weaponry has been getting developed, namely keeping the launching platform and pilot/crew safe. A US$60 million+ F/A-18F Superhornet is an expensive piece of kit, and then there is the time and cost of training the pilot (AFAIK ~US$5 million+) Neither of which can be replaced quickly or with little cost. By keeping the launching platform farther away, the defender can lose the ability to either see or shoot at the aircraft.
As for #3, the defender likely would not be able to tell exactly where the ordnance was headed until it got rather close... By which time it might well be too late to successfully engage.
As for the Falklands example, the RN SAM defenses were geared towards mid-range high altitude intercepts as a result of Cold War planning. It is likely that had the Argentinian Air Force used such standoff weapons at the time, then likely yes, many of them would have been intercepted. However, one would have to wonder, just how many A-4 Skyhawks Argentina would have lost in that sort of engagement, and if the RN would have had more vessels damaged or lost. On a cost basis, assuming Argentina planned ahead and had built up warstocks beforehand, I think it likely that the RN could have found itself either suffering heavier losses or forced to withdraw. Either the RN would be forced to conserve the missiles carried aboard the frigates and destroyers and only engage aircraft thus ignoring bombs which would air and strike ships, or the missiles could target the bombs which would likely be available in greater numbers than SAMs.
Also, keep in mind the scope of engagements. Diferent sized and typed ordnance is available for different mission profiles and are used as such.
-Cheers