I'll take a swing as well. I may be misreading the question but I don't believe it is an "either or". I believe the answer is "yes" to both sides of the question. First, I think the vast majority of today's motorcycles are designed for their intended use. In the broadest sense think dedicated dirt bikes, trials bikes, track bikes, touring bikes, etc. Their frame and steering geometry, suspension set-up, basic rider ergonomics, engine choices, etc., are all designed with a purpose or specific rider use in mind. However they are also designed within the limitations of today's technology and materials science knowledge, plus the economic realities and limits of what consumers will pay for a given motorcycle's capabilities.
With regard to "do we need to do something to keep a motorcycle in its operating envelop", my initial reaction is to say we do it every single time we ride when managing things like throttle and acceleration levels, braking force, lean angles and traction limits for the specific riding situation we happen to be in. And we all know what can happen when we exceed an operating envelop.
Just an add-on thought to this. What I love about many of today's motorcycles is how technology (e.g. ABS, traction control, engine braking, wheelie control, slide control, various riding modes, etc.) is being leveraged to help us safely stay within a motorcycle's operating envelop, AND that we can adjust the parameters of the envelop for our various skills and capabilities. I can't even imagine where motorcycle tech will be in another 20 years, but I know it will be fantastic!
I've heard people say we're in the golden age of tire tech, but we might even be able to say that about the software / sensors / ECU technologies of today's motorcycles.
Dave