This is as difficult a question to answer fully as any deep philosophical issue in my view Ren.
My feeling is that elegance in concepts and elegance in expression are two sides of the same coin and they are strongly correlated. If the elegance is lacking, the concepts are almost certainly not well defined. This doesn't matter too much in exploratory work, but vital in the finished work - and is true in all complex subjects, not just philosophy. I don't agree that such elegance must necessarily include accessibility by lay people, and this will depend on the purpose of the work. I guess being brought up with degree level maths, I'd say that in general the first obligation is to precision sufficient to the purpose of the philosopher acting within his ground (in OM terms). Intelligibility to non-experts may or may not lie within the scope of that purpose depending on what it is. For example, I find it hard to conceive of Marx getting very far without a widespread accessibility of his ideas. Whitehead and Russell don't need to communicate with anyone other than fellow experts to achieve the aims of Principia Mathematica - and I can't imagine how you would translate such a work into anything understandable by a layman other than by using metaphors which would only scratch the surface at best. I'm sure the work Asa mentioned is similar, but I haven't looked at that.
I have no objection myself to an inspired philosopher expressing ideas in a way that is difficult for me to grasp directly. This is no different to the way my interest in cosmology works - I have neither the patience not the interest to read the technical and mathematical work done in this field. I can satisfy my interest completely by reading the layman's literature - though sometimes this does trigger my curiosity to look more deeply at the professional stuff. But I defy anyone except a highly specialised mathematician or theoretical physicist to deal directly with 11-dimensional topology in the expression of string theory - and these guys are over the boundary between science and philosophy in a number of ways. Making it accessible by lay people needs a different sort of skill to that of the researchers – and the guys with that popularisation skill are unlikely to be at the pinnacle of the research ability themselves.
Looking at the topic from an alternative angle - we each have widely differing abilities. Some people struggle to understand what's in a tabloid, while others can grasp the outer reaches of philosophy without much mental exertion, and there are lots of stopping off places between these two. Then there is motivation - a less able intellect may be very comfortable with Kant because they really want to understand and are prepared to put a lot of effort in, whilst a more able person who isn't all that bothered gets pissed off quickly with all the cant and abandons the attempt. I'm sure there are varying expositional abilities among the Greats as well, and maybe some who are deliberately obscure. I think the ideas and their capture are more important than their ability to express them so that non-experts can understand them - maybe no-one else would come up with the same insights for hundreds more years! And some are perhaps deliberately obscure - there are works that were made esoteric in the Middle Ages so they wouldn't fall into the wrong hands and be misinterpreted, or lead to the arrest and execution of the author.
Then there is the question of what sort of apprehension we seek individually. I quite appreciate an intellectual (thinking) kind of access myself, but what I really want is Ni insight, and if the intellectual approach doesn't lead to that insight, I am not viscerally engaged. But the kind of exposition that really connects with me may not engage someone with a very different temperament. I have been introduced to some of the most profound ideas through works of fiction and fantasy as much as through the great philosophers. For example, David Lindsay's "A Voyage to Arcturus" has given me a vivid Ni feel for gnostic ideas in a way that the gnostic gospels certainly do not - even though it is quite gauche in its literary style, the symbols it presents are extraordinarily compelling. Of course, this sort of exposition isn't going to deliver a synoptic appreciation of gnosticism, but it lights the fire within me and that's what I find lacking in many philosophical works by the masters. My own ask of the philosophers is to cut all the verbiage and just give me the deep insight - I don't need the justification because that arises directly for me “consubstantially” with the insight. This isn't a criticism of the masters and it doesn't absolve then from full intellectual expositions and justifications, which are vital - it's an illustration of how difficult it is to provide an exposition that appeals to a wide range of people, because we are all so different in what engages us.
A book I have been reading recently is "What We Can Never Know" by David Gamez. It is a defence of positive scepticism, though I suspect with the author's own slant on the subject. It is a really good read, well written and it fired my imagination and enthusiasm - the way he expresses his ideas rang a lot of echoing bells for me and I was able to internalise a lot of his concepts almost effortlessly. It is not a professional philosopher's exposition and to my mind is an excellent example of a book on a complex philosophical subject that makes it accessible to lay people. It works for me! David Gamez is the nearest we may be able to get to an "applied" philosopher. His main work is on the practical creation of artificial intelligence and I have attached a link to his PhD thesis details. It is fascinating because he is trying to take deep philosophical ideas about consciousness and convert them into practical implementation in artificial intelligence devices. This is the web link:
http://www.davidgamez.eu/mc-thesis/index.html
I have done no more than skim through this material, but it looks like a pretty glorious example of intertwined easy to understand and profoundly difficult material - and why would we expect anything different.
I do love the idea of applied philosophy - it seems to make it come alive .....