I like the open source concept, though I think making it more universal is more appealing.
Wheel Hub motors are, by definition, in the wheel... So, that would mean that the weight of the wheel will be greater than a conventional wheel design. The higher the capacity of the motor, the more it is likely to weigh.
Given the above, a wheel hub motor would seem more applicable to low speed use, or applications where suspensions are a secondary consideration, due to the inherently higher un-sprung weight.
I agree than defining the objectives of the motor are important at the start.
I think a wheel hub motor would be well suited for applications such as garden tractors, material haulers, electric mule, forklift, etc. 40kw would be overkill for most of these applications. However, I have read on the website of one manufacturer of wheel hub motors, that they can be mounted inboard of the wheel, and couple to the wheel though a drive axle (one motor, one wheel). That makes sense to me in terms of keeping unsprung weight down, even using one to drive a conventional auto RWD axle, keeping the differential, or two for 4WD.
I suggest keeping conventional mechanical brakes because at some rpm point, it will take energy to slow it anymore, and it will definitely require energy to hold position against an outside load, so for full stop or parking, conventional brake are hard to beat.
With regards to the controller. I am very interested in learning more about design and building a controller for my future EV project. I have found that there are many electrical CAD packages out there, I found one called Dipfree 1.5 which has a freeware version. As I am pretty ignorant about integrated circuits at this point, I don't know if it will help in design and understanding. I am quite familiar with CAD/CAM software for use in CNC routing, so I know that mere possession of a tool does not equate to proficiency with the tool. I do hope, however, that possession of this electric design tool will help me learn. I have been watching another thread on this board regarding an AC 3 phase controller, but it is still mostly over my head technically.