It should be noted that Speechcraft isn't just more useful in order to raise Disposition, but because of Sway, Haggle and Debate checks in dialogue. Unlike in vanilla Morrowind, where convincing someone to agree with you is usually just a case of the NPC having a Disposition of approx 70+, TR relies a lot more on your Speechcraft skill so that you can't just bribe your way through every bit of quest dialogue. As you can see in the wiki article, what makes it a bit more interesting is that, yes, an NPC having a high Disposition towards you does make them more likely to agree, but it's not strictly necessary. This means that a master of Speechcraft can even convince their enemies to agree with them.One skill that feels way more useful than in vanilla is speechcraft. It still functions in the old bribe-intimidate-admire way to raise an NPC's reaction, but there are way more quests where persuasion is a possibility, or where the outcome of choosing a dialog option depends on an NPC's reaction towards you, so using speechcraft to raise an NPC's reaction pays off way more than it did in vanilla Morrowind.
It's interesting because this is all entirely new and it makes better use of Morrowind's mechanics than just Disposition or just skill checks in dialogue, the latter of which are present but exceedingly rare in vanilla.