Tools for the job
Did someone just pull that list from Wikipedia without thinking about it?!
Admittedly, storm shadow is stupid on Harrier, but it is provisioned for it, but not cleared.
Brimstone was in the process of being cleared, but they were dragging their feet possibly because Maverick was operational and filling the role, why spend money while they are still in stock
ASRAAM was cancelled for Harrier, seeing as it is a bomber and sidewinders are still pretty capable, it's fair enough - if you need air cover, bring Typhoons.
Litening 3 does the same job as the Sniper pods carried by Harrier
RAPTOR is a recon pod carried by dedicated Tornado platforms (GR4A) with very limited strike capability - These could possibly be kept on like we did the recon Canberras in the event of ditching Tornados.
Enhanced paveway III, so what, Harrier carried Paveway IV.
ALARM - Gulf War 1 era anti radar missile, well Harrier never was a SEAD aircraft, Typhoons more suited to this, early-ish Tranche 2 aircraft should be able to carry it.
And the whole point about the RC-135 aircraft - There are hundreds of them out there, that means they are going to be cheap to run and maintain with greater availablity, instead of having to custom make each part like they did with the Nimrod, when parts fail