Yeah i think that is Frontiers philosophy of UI design, extra steps are good, especially in a game, where spontaneity and immersion dont matter.
Regarding immersion, the current launch button was always a problem for me. Being able to take off at the second you decide it, without having to wait for control tower clearance and implying that our engine was always on, has always felt very gamy to me. I got used to it, as I understand the wait could get tedious (not as much as the check list idea) ; although I'm not sure how tedious it would be as I've played game that had cinematic for such moments, and I would get used to it. But I still have this in the back of my mind everytime I take off a starport or a station. It kind of ruined my immersion a bit, but I kind of also appreciate not having to wait to be on my way. The long press (which is called like that just because it takes a couple of hundred milliseconds more than a normal click) is not a wait.
With that mindset though, it could be argued that we should probably have to wait a bit more for docking too, but since we're in motion, landing isn't instantaneous, and as there's an audio cue to have us believe we have chatted with the control tower, it feels more like a natural ellipsis about what would really happen. I wish there was something similar before we take off. but I understand it would get on the nerves of less patient players that are not that interested in the simulation part, but in the gamy part.
Back to the suggestion and regarding immersion, UI lag and accidental launches are still quite frequent (actually it shouldn't happen), and are way more immersion breaking, like totally.
your mention of "spontaneity" reminds me that in Frontier:Elite II, on planet starport, you had the choice to take off without asking for clearance, but it would make you wanted, and you would be chased by dozens of police vipers. That was a bit extreme, but I liked that we still had control over our ship and could take risky choices (for example, for an assassination mission when following a target). But you could accidentally hit that button. That was counter-balanced by the fact that the game was offline and could be saved at any time.
In that case, and in the current situation with the launch button, being able to take off by mystake (whether because of the ui, or because you decided too quickly) is immersion breaking as it reminds you you're in a game, since in reality you would go through a different process ; that doesn't mean we need a check list everytime. It means there should be just the right amount of involvement, a small audio/visual cue that plays out like a quick ellipsis to express what you would been doing in reality, and that could fix ui problems on many machines.