The challenge for the designer today is to produce ecologically-sound buildings without compromising contemporary concepts of beauty. There are plenty of examples of excellence in sustainable design which is soundly built, well-fit for its purpose, and an aesthetic delight. Even small luxury home plans are increasingly ecology-conscious in their choice of materials for conservation of resources and self-sufficiency.
Aesthetics is in the eye of the beholder, and it depends upon the prevailing tastes of the time. A building's functionality, or fitness, is a matter of how well it accommodates the purposes for which it was built. Its structural integrity means soundness - will the building last over time? Historically speaking aesthetics has usually trumped fitness as the overriding factor in architectural design. Classical architecture was preoccupied with articulating features on walls and facades. Modern architecture is equally concerned with aesthetic formalities, such as form following function.
Nowadays cottages are often used as summer or weekend getaways - often by lakes or the seaside - by urban dwellers seeking to escape the noise and rat race. They are often built as rental properties in popular tourist areas. But usually when people think of a cottage they mean a rural dwelling in the traditional English country cottage house plans style with stone or stucco siding, asymmetrical lines, one-and-a-half stories high, and with hip roof and steep gables - the overall impression being a cozy, storybook appearance.
Given their professional experience in house designing, it can be helpful to hear why certain elements will and will not work as you may envision. Your architect will be able to show you 3D walk through plans too. This can be useful exercise to examine sun patterns at different times of day and get a feel for the scale of your future modern home.