I think most of the problems in theoretical philosophy are not so profound but rather result from the misuse of language. For example, Take the ancient question "why do we exist? " I believe the question is simply unanswerable rather than unsolvable profound. First, Consider the word "why". We use why in situations where a statement or fact and be reduced down to its constituent axioms. For example, If someone tell you the the sum of all angle in a triangle is 180, You may ask the person "why" to make him reduce this fact to the 5 postulates of euclidean geometry. Asking why does energy conserve is asking for a decomposition of that statement to newtons law. Overall, We see that "why" is only applicable to "theorems" and not "laws" or "axioms". For example, Asking why 2 lines never meet if the interior angles sum up to 180 is simply nonsense for there can be no why explanation for an axiom. Similarly, The fact that we exist is taken as an axiom because how can one prove that he indeed eixsts. And consequently, It is nonsensical to demand a why explanation for our existence.
In the course of human history one band of knowledge has been able to answer questions that science (originally called natural philosophy) and Theology could not answer and that was philosophy. The existential questions asked by philosophers have helped us learning more about world around us it has even helped in our understanding the principles of certain disciplines such as the sciences and Theology. It was Socrates who said I know that I know nothing. Let me give you an example. One Existential question is what are the laws of logic and the rules of reality, How do they work and are they based in human cognition or another source or how about this one. Is Moral Realism true what is the moral code, Does it exist? What is the true branch of metaethics? Questions like these are serious questions that need to be asked and need to be answered through serious non biased debate. I would argue the poster of this opinion does not appreciate the intellectual system that has influenced human society more than any other knowledge and belief system.
First, we must assume that language exists as a way of symbolizing both tangibles and abstracts, and that each symbol exists as a way of classifying and even parsing reality into its constituent parts. We could then assume that it would be remiss to leave any symbol in a relatively simplified state, as it may be too general in its description of the original form. Of course, any descriptive system that exceeds the complexity of that which is described is inefficient, but just as physics has allowed us to understand subatomic particles, so does language with ideas.
The issue that seems to be in debate is not about Theoretical Philosophy as much as it's about the etymological background and value of asking questions for which no answer is readily available, or ever available. "How can one prove that he indeed exists" is often taken, not as a challenge to open a black box, but as a belief in a presupposed axiom. The basis of human understanding as it exists is to question the previously supposed axioms to reduce, if at all possible. The basis of my argument is that assuming that an axiom is always irreducible only allows arguments to be built off of assumptive reality and not empirical or observable reality. Axioms, by nature are assumptive, but not infallible or unquestionable. Only by asking the questions can we find their nature, so that asking why we exist is simply a way of questioning the axiom. When asking why we assume that we need to find better ways of observing the parts of reality that are minute, subatomic ideas, if you will. Also, just as mathematics requires "0" when an absence exists, so philosophy must require something much the same.
Therefore, questioning axioms is not in of itself useless, but is not often expedient except to find that the axiom remains.
Think in 3D, my friends.