One of the theories for why Earth doesn't have a similarly dense atmosphere is because we have the Moon - a large gravitational body nearby strips away the atmosphere enough to prevent the endless buildup like Venus has.
The atmosphere on Mars by comparison is awful for landing spacecraft. It has just enough density to jumble the craft's trajectory, so vacuum-based EDL techniques similar to the moon landing are impossible, but it's too thin for atmospheric EDL systems similar to those used on Earth.
Atmosphere (especially a dense one that causes drag and heating) makes achieving escape velocity harder, as you need to actually do it 'high up' where the atmosphere is not as dense, say from something similar to Low-Earth Orbit.
I'm well aware of that, I think you didn't see what I was trying to say.
> as you need to actually do it 'high up' where the atmosphere is not as dense, say from something similar to Low-Earth Orbit.
That was actually the thought process behind it, not the problem with it. I will rephrase it:
On earth piggy-backing or ballooning a rocket to the upper atmosphere is not usually practical due to the ability to produce lift in the atmosphere relative to the size and weight of the rocket.
However, on Titan with a thick atmosphere, imagine flying one to the upper atmosphere which would take relatively little energy in a thick atmosphere with low gravity, thereby escaping much of the problem of atmospheric drag and using it to your benefit instead.
That's just the thought process, of course I don't of anyone that has done the math on the most efficient way to launch from Titan, yet.
exp(-gravity * height)