Assuming I have the right tool btw... For me, (in the last version I used) the UI leaves a bit to be desired. The complexity and interdependencies of the toolbars (ribbons?), for example, has steepened the learning curve a lot, simply by tring to find what is available and where things are. I understand why it has been done that way, but I think it needs to be made more simple. After all, it is going to be teachers and scientists who will, I suspect, be the main audience, and maybe students who will have to be able to use it. None of these groups have the time, nor, in many cases, the inclination, to develop an understanding of a complicated tool. (e.g. Look at the difference between Office 2003 and Office 2007 and why Office 2003 is still the preferred candidate for many people and organizations, simply based on the complexities of the Ribbon structures. It is changing but I am surprised at the number of places I go and they are still using 2003.)
Having said that.. mmm now that there has been a growing acceptance of that kind of change, it may very well be more acceptable. Dunno.. maybe. The real test, Is suspect, is going to be when sufficient number of schools for example, have their Moodles and are taking the development of their Maths resources seriously. Wont be business, nor Universities, it will be if Maths teachers can take Wiris and use it without a great deal of thought, something Maths teachers, I observe, tend to find very difficult. If they can use it and promote it, then it will be accepted, but if they find it "too hard" they will keep looking until they find something that they find "simple" to use. Will not matter what anyone else thinks if they like it, they will use it. Its a bit like "Build it, and they will come." but they have to be able to grasp it and be productive in the first few minutes or it will be "too complex" or "too difficult".
As to how you can simplify that, I have no idea, I don't design UIs, but I can say that the more complex the UI is, the less successful it will be. I hear terms like "intuitive" but the only time I see "intuitive" is my brother seeking out chocolate, or people finding answers to questions without any information to go on. Keep working on it... and, hopefully, you will prove me wrong.