Most of the inertia from HLVs is wasted on the rocket itself. Ultimately, you're stacking an extra hundred tons of rocket just to get an extra ten tons of payload into orbit; it's not getting up there all that much faster, UNLESS you count some sort of huge Earth departure stage (which is cheating, by the way).
The only reason to use an HLV is if you don't have the patience to use cheaper EELVs to do the same job piecemeal. Thus America's first space station was built on the ground and tossed into orbit on top an HLV (Skylab on a Saturn-V). The Space Shuttle, arguably, was also an HLV if you count the mass of the orbiter as payload, but that still meant building the station piecemeal, and with the shuttle's lower payload it was essentially a highly expensive MLV.
In the end, we no longer use HLVs to launch space stations because we've discovered that we can build larger and more efficient structures using the tinkertoy approach. The same would be true of interplanetary missions for the same basic reason: you can build a larger spacecraft with much more propellant and much better equipment if you don't have to fit the whole thing onto a single rocket.