Well the HLV isn't going to cost 20 billion. Thats a figure floated by its enemies within NASA. Also EELV launched modules will be even more cramped than Shuttle launched modules--where the shuttle did all the lofting, docking etc. HLV advocates were around long before it became pork. Selling lots of EELVs is pork too, especially if you are constantly launching say, 36 D-IV heavies or 24 F-9 heavies to do what one or two HLLVs can do. Five of them and ISS would have been finished with most of its useful life ahead of it, not behind it.
Ares V was going to be used for a piecemeal optical system: http://up-ship.com/blog/?p=9363
SLS can launch a goodly sized scope on one shot as well
Ms Porco from Cassini knows her stuff. Proton was a manned station launcher before placing a rover on the moon. As far as NRO giving those spysats away, you might want to look at the post of this JPL man:
This examination shows there is no significant cost savings by pursuing the use of numbers of medium-lift vehicles when compared to the development of a new, shuttle-derived heavy lift booster.
And neither of them seem to understand that SLS will leave no money to develop those missions they want.
SLS will not always be in the development phase. Remember, we sustained over 100 STS missions that were HLVs in their own right It was just 90 to 100 tons of that was the orbiter. Now it will be all payload--payloads no one thought to ask for before the capability. People want to raid SLS budgets so they can keep launching Delta II sounding rockets and are being small minded and petty. That is what Carolyn refered to. delta II launches are like lollypops an alcoholic father gives to kinds every five minutes to keep their traps shut. Better to spend that money on a filling meal at the end of the day--even if that means listening to their squawks
Now imagine if we had flown 100 Saturn or SLS missions instead of shuttle missions-- and imagine at what we might have up there now--maybe even something like this: http://up-ship.com/blog/?p=15169
Nice fictional model of a shuttle: