Why can't wizards use magic to clean or organize their house, or even to prepare food, for example on Weasley's and Black's house?
Molly Weasley in particular is seen using magic to conjure ingredients, boil water, and so forth.
Presumably such spells, like all others in the Harry Potter universe, require practice. This means that it takes time and effort to replace manual labor with magic, and each spell is specific to a task. Some wizards may not have the patience or skill to do this, so different wizards use different levels of magic in their chores.
There are several instances of Molly Weasley cooking and cleaning using magic. There are three different instances of the spell Tergeo being used to clean every day items (Hermione cleans blood from Harry's face with it, Ron uses it to clean a rag, and Harry uses it to dust).
However, it's more likely to be used by a family such as the Weasley's, whereas when you start getting towards more affluent wizarding families such as the Blacks, Malfoy's, etc., you are more likely to see them with servants such as house elves to do their every day work.
Many wizards can and will use magic to do household chores. However, underage wizards are not allowed to use magic outside of Hogwarts, so Hermione, Ron, and Harry were not allowed to use magic to clean Sirius's house. Mrs. and Mr. Weasley, Bill, Charlie, Fred, and George all were able to use magic at home to help with chores, and in Harry Potter and the Order of the Phoenix, Fred and George flaunt their priviledge in front of the others by using hovering spells to put food on the table and by apparating throughout the house.
Also, in Harry Potter and the Chamber of Secrets, when Harry had first arrived at the Weasley household, there had been pots and pans hovering above the sink and being cleaned without anyone in the room.