I'll talk about these in reverse order. First,
Is it valid to solicit answers in view of a particular presupposition, or systematic theology?
This is pretty easy and straightforward to answer: No. Systematic Theology is off-topic. We will typically refer these types of questions to Christianity.SE or Mi Yodeya. This has been done to help to make ourselves distinct from these other sites and prevent overlap.
(side note: this should probably be a meta question, but I think the rest of the question may be appropriate for the main site.)
Second,
What makes hermeneutics more than academic humanities?
This is a little bit harder, as it depends on what exactly you consider to be "humanities." According to the very same Wikipedia page you cited above,
In the Middle Ages, the term [humanities] contrasted with divinity
And so the distinction was very clear. You were either studying humans, or studying the divine. It wasn't so important how you studied and study of the two different subjects might be done using similar or identical methodologies.
This makes the distinction between hermeneutics and Biblical hermeneutics very important. One is studying humanity, while the other divinity. It is also helpful to know the etymology of Hermeneutics. This term derives from the name Hermes who was a messenger of the gods. (or perhaps it is the other way around, he was named as such because he was a messenger and the Greek word ἑρμηνεύω (hermeneuō) means "translate" or "interpret".
The Greek view of language as consisting of signs that could lead to truth or to falsehood was the essence of Hermes, who was said to relish the uneasiness of those who received the messages he delivered.
-Wikipedia
Thus hermeneutics (especially Biblical hermeneutics) can be thought of as the translation and study of messages from the divine, their delivery, how they are understood by their audience.
In modernity however,
Today, the humanities are more frequently contrasted with natural, and sometimes social, sciences as well as professional training.
(again, according to Wikipedia)
So in some respects, today, this is more of a Venn Diagram in which parts of Divinity and the Humanities overlap. Because we have a significant difference in perspective from other cultures, and several thousand years of dogma create certain biases in perspective this radically different staring point causes us to see the original message from a different perspective and understand scriptures in a different way than their original audience - which sometimes leads to radically different, theologically significant and impacting conclusions by modern westerners that an ancient middle easterner would have seen differently.
Several thousand years worth of the Hermeneutic Circle have spiraled our understanding away from the original meaning of the message. The best way to combat this then is to attempt to reset our perspective and try to start from the mental framework and perspective of the original audience of the Biblical texts.
The best way to combat this problem and regain a pure and original perspective this is to peruse academic disciplines (humanities) such as archaeology, textual criticism, study of Biblical Hebrew, history, cultural anthropology, geography and more. The more we do this, the better our hermeneutics are likely to be.
So, In short, yes interpreting texts based on modern spiritual values and understandings represents poor hermeneutics. When questions come from view with a particular theological presupposition, we have put the cart before the horse. Theology (should have been) derived from the message. If we use those philosophical/theological conclusions in interpreting the text, then our interpretation will only be as good as our philosophical/theological presupposition - and clearly there are many conflicts (Eg, Arminianism Vs. Calvinism, the necessity of baptism for salvation and so forth). So that means at least half the time in these cases, if we make a presupposition we have proceeded from a false premise rendering our secondary conclusion "invalid" and useless in half of those cases.
The implication here is that the more presuppositions we bring with us, the greater the likelihood that our conclusions are wrong because the issue becomes compounded. Obviously, we do have to start from some premises, so there is some bare-minimum theological presuppositions reqired - but the goal is that the premises we begin from be as identical as possible to the original audience and that we share their theological presuppositions when reading the text. This tends to put "Good Hermeneutics" and systematic theology at odds wherein the more presuppositions you include, the less likely you are to have a good hermeneutic and the more academically rigorous you approach the text, the greater the likelihood of achieving a correct understanding. (and so I hope you can now see why systematic theology is off topic)
Now, this isn't to say that that you won't reach some of the same conclusions and positions as the great historical thinkers of Systematic Theology and church tradition, but sometimes your conclusions may be divergent.
But most importantly questions generally shouldn't start from a conclusion. Because doing so skips past the hermeneutics and has moved on to something else entirely. And this is why answers that solicit answers based on spiritual values and particular (systematic ) theological presuppositions are off topic. They have skipped the hermeneutics. Conversely, this is why Christianity.SE frequently requires questions to ask from a specific perspecitve, viewpoint, tradition or denominational view, because they don't want to steal our thunder.
