Simply because - the shape allows the contents to exert even pressure throughout the vessel.
takes shape of its containerThey both flow and have shapes defined by their containers.
The state is gas. Gasses can expand and be put in containers of different shapes.
spherical, ovoid, cylindrical.
Non-cylindrical objects are objects that do not have a cylindrical shape. This includes objects with irregular shapes, such as spheres, cubes, pyramids, and cones among others.
Cylindrical objects are three-dimensional shapes that have straight sides and circular bases that are parallel to each other. Examples of cylindrical objects include cans, pipes, and drinking glasses.
Transformers come in many shapes. Cylindrical, square, and rectangular are three of the main shapes of transformers.
The premise of your question is false. Take, for example, a juice box.
Cylindrical shapes are efficient for housing the components of a battery, like electrodes and electrolytes, in a compact space. Additionally, cylindrical shapes provide structural stability and prevent leakage of the battery contents. This shape also allows for easy stacking and packing of batteries in electronic devices.
The shape of stoneware vessels changed in the mid-nineteenth century. Classically ovoid shapes of crocks and jugs became more cylindrical; thus stoneware containers can be dated by their shape. Ovoid vessels date from the first half of the nineteenth century, while cylindrical containers date to the second half. Do a Google Image search, or look on E-bay for similar ones.
Gas diffuses in space.
Most fire extinguishers contain a powder with a pressurized propellant, or sometimes just a pressurized gas, and occasionally a liquid under pressure.Round containers are best for pressurized containers because they retain their shape under pressure. Most fire extinguishers are cylindrical shaped with either concave or convex ends.
In brief The most efficient shape for withstanding high pressure is a sphere but that would be costly to manufacture. A cylinder with a domed top and a domed bottom (look underneath, the flat base is actually welded around the outside, the bottom of the gas container is actually domed) is a much cheaper shape to manufacture whilst still having good stength to resist the internal gas pressure.Some other ideasThe idea that "cylindrical vessels have minimum surface area to volume ratio and thus reduces heat transfer" is incorrect. The surface area to volume ratio for a cylinder depends on the ratio of its length to its diameter and most cycinders are manufactured with a much greater length than is ideal for minimising surface area. In fact a cube would be a better shape than most gas cylinders if this was the primary design consideration. Also heat transfer is actually often a good thing for gas containers, liquids require heat to convert to gases. Try using a butane cylinder on a near freezing day......The idea that "they are cylindrical because there are no weak points such as joins and corners that the gas molecules could force apart" is partially correct, a cylinder with hemisperical ends has no corners which would certainly act as stress concentrators and therefore be much weaker for the same material thickness but many low to mid pressure gas containers are welded from sheet material so there are joins.