I really don't know why people are claiming that there is no variation in that scene. It's simply not true.
Paragon...
S: "I appreciate the thought, Joker. But I'm fine!"
Joker and Shep are still best buddies.
Renegade...
S: "When I want a damned pep-talk, I'll ask for one. Otherwise, you're my pilot, not my therapist. Is that clear?”
Joker is mad for the rest of the game, you can apologize later
The tone is completely different, Jokers reaction is completely different and the rest of Jokers dialogue in the game plays out differently. I mean...ok, you didn't get the option to laugh (and I found Shepards reaction too mild after Joker's racist slur), but it's really not the same. This is even one of the rare instances where NPCs remember how you treated them.
That's not the part we're reacting to. Never has been. It's the first one. The one you find 'too mild.' You want to be more extreme, fine. Me, I hear that as a lousy joke made as a part of attempting to cope with a horrific event - I have done the same thing. I have been in the midst of traumatic experiences, and my method of attempting to cope, to process, accept, and deal with the things I'm going through is to make really crappy, even off-color jokes, because for me, it's laugh or cry, and if I cry, I break down and become effectively useless. I see Joker being the same, and he is in a position where he can't afford to be useless. So I get where it's coming from. I understand why he's said that, and, even if I don't agree with the statement, I get why he's saying it. I would accept a three way option there - a 'not now Joker' style choice, one of the options from what is there in game, and your preferred rage. I don't mind you getting what you want as long as I get what I want as well. Instead, we are getting two variations on 'how dare you act like this in reaction to Thessia falling?!' THAT'S what people mean when they're saying you're getting variations on a single reaction, rather than a choice.
Thessia's aftermath is a certified clusterfuck in terms of characterization, because we don't get a single word of input on how Shepard is taking things. Everyone talks at Shepard, telling them 'don't take it personal' or 'you couldn't have done anything.' Here's the thing: I am in full agreement with them. Thessia fell before Shepard arrived. The beacon in the temple was no magic 'I win' bomb. Even if Cerberus hadn't stolen the data, the planet was still under assault from a full invasion force of Reaper troops and at least one Sovereign class Reaper (most likely there were more we didn't see), which in ME1 took entire FLEETS to take down, and lucked out with Sovereign devoting much of its processing power to fighting Shepard via Saren's corpse. Shepard did everything they could, and from my perspective shouldn't be beating themselves up over this. But that's what I get from their dialogue. Direct quote from Shepard: "Thessia's fallen and that's on me." NO. IT. IS. NOT. There is a whole chain of responsibility to Thessia's fall, at least five links in it before we can think of getting to Shepard.
And as for Liara with Javik, she was looking at him not as an individual, but as the Wise Prothean Elder. She says explicitly 'you were supposed to have all the answers!' during that confrontation. She is blaming Javik for not being what she expected of him and the protheans, and he's having none of it - he's not responsible for her pre-judgments of his species, seen through her own lens (she makes it clear on Eden Prime, she is viewing the protheans based on what she wants to see - 'They uplifted countless other species to help them join the galactic community. The protheans wanted other species to learn. It's clear that they prized knowledge, growth, and cooperation with the rest of the galaxy.' Take the paragon choice after that, she admits she's coloring them on her own perceptions. She wants Javik to be what she wants the protheans to be, and gets mad at him for not being that. Javik himself is in the midst of his own PTSD of learning that he is the LAST PROTHEAN IN THE UNIVERSE, that everyone he knew before is long dead and what remains of his species have been turned into servants of the same machines that they once fought. The whole game, Liara wants to treat him as a lab specimen, a living archive she can peruse at her leisure, and Javik has no patience for it because he's STILL PROCESSING this loss. Liara is lashing out at Javik for not having answers she wanted him to have, and not liking the ones he did have.