On one way of understanding your question, the answer seems not just to be "No," but "Hell no!"
What I mean is this: the discipline of philosophy isn't a mystical practice. Among its most important techniques are careful analysis and well-reasoned argument. The kind of thinking philosophers pursue needs to be embodied in a rich and subtle language. And on one meaning of "conventional" -- i.e., based on shared conventions and meanings -- we would be unable to communicate successfully without the conventions of language.
Now for a couple of caveats. Good philosophical ideas might come by any number of routes, including sudden bursts of insight. But the discipline of philosophy calls for shaping and articulating those insights. And if by "complex language," you mean bad, bloated writing, then indeed that can get in the way of understanding. But this goes for any discipline; not just for philosophy.
So yes: philosophers sometimes smother their ideas in a blur of verbiage. But good philosophy really does need needs sharp, subtle linguistic tools.