With the ranking of missions and the threat levels of signal sources (and of course the farming zones), this is important. This is the way that players can have a 'difficulty slider', and FD can tie reward to risk.
I get the impression that for some players, the new mission system hasn't yet been fully understood, and that they may be taking high paying and high ranked missions and then being surprised when they encounter a high level NPC opposing them. Personally I would like to see much clearer information in the mission description. "We want you to deliver this stuff, but be aware that Bob the Elite Anaconda Monster is on the trail of this stuff too!"

Might make players stop and think whether they can complete the mission, or even help decide what ship to use (if they have a choice).