The Deliberate Decision - When To Go Manual With A New Lens
Well the manufacturers of digital camera bodies all give you lenses from their stables that are perfectly suited...each to its own mount. They have generally worked long and hard to have a wide variety of optics in all sizes and focal lengths - and they will generally have a range of prices for them as well. You pays more, you gets more, but since the lenses are good to start with, the extra costs can sometimes be a diminishing return.
Enter the independent lens makers - companies who may have a license to use the mount of a certain camera but are not restricted as to what the other specifications need to be. They can search for the niche market that wants a particular focal length or maximum aperture. They sometimes elect to leave out auto-focus and auto meter connections to make the lens universal - they figure that if you are advanced enough to want a specifically special lens, you are capable of focusing and stopping down yourself.
The stop-down question is not even addressed in many cases - you get a good old click-stop aperture ring and are in command of it every time you shoot. If you are a maximum-aperture freak you just cello-tape the aperture ring open and let it go at that...put the camera on aperture priority and let it sort out he exposure. In most cases it will guess better than you can anyway.
Note that there is a good bayonet fitting for a lens hood but none is packed in the box - presumably it is an extra.