I've long ago given up on finding the perfect all-season motorcycle riding outfit. I'm sure we'll see it some day, when fabric technology evolves to Star Trek levels.
How about some type of lightweight, form-fitting, comfortable do-it-all garment that keeps us warm in the winter, cool in the summer and wrapped in a protective cocoon? Dream on...
In the meantime, niche garments are basically the only way to go. Sure, there are a few outfits that will work in a wide range of temperatures, but it's the extremes that blow the plan.
An outfit that works in very hot weather is not going to work when the snow flies. Something that keeps you dry in a downpour is probably going to make you sweat any time it's not raining.
It kind of follows the classic bell-shaped curve - there are many combinations of jackets and pants that will work for the most common riding temperatures, covering a range of about 65 degrees Fahrenheit to 80 or so. But for the extreme outliers -- the 3+ sigma tails in the normal distribution -- only specialized clothing will do.