Yes, but there's another variable in speech checks - the person you're speaking to! Just because you have a high speech skill doesn't mean you can convince everyone.
Of course not, but the issue is, what mini game would they create to reflect player skill?
Science requires skill to access a minigame that requires anolytical thinking: the skill level is nothing but a key to a game that requires player thought. Same with lockpick: it's nothing but a key to a minigame that demands player perception.
What minigame would they do with speech? Different people have different opinions on what the "best" statement is, and people interpret speech options differently. If they were to make it so that speech unlocked a menu of POSSIBLE correct answers of persuasion, people would probably complain about those. One person might complain that the correct answer was a lie and they don't want to lie, another person might complain they misinterpreted one of the speech options, a third person might complain that they chose a wrong speech option because it suggested a possibility of getting an answer/response that they themselves were more interested in, etc.
Speech is kind of hard to categorize with a mini game because there's no such thing as a correct answer. Whereas a failed hack attempt reflects a failure for the player to think anolytically, a failed lockpick attempt reflects a failed amount of perception, a failed speech check in a system like the one I mentioned above would demand a very good character design as far as NPCs go, or else players would complain that it's bull that they're being punished for not understanding the NPC's bland personality enough or for being able to misinterpret the impact of a response.
Thus, until they come up with a fitting minigame to reflect speech, I think the current system is best.