Tony likes films with lots of gratuitous violence.
Films with lots of gratuitous violence are liked (by Tony).
Might I enquire of you why native speakers do disallow/dislike this passivisation?
Partly because it is less direct and more verbose, but the main reason is the content of this particular sentence is not really suited to the passive voice.
The concept of "to like" is naturally very dependent on the identity of the person who does the "liking". The relationship between the thing that is liked and the person who likes it is essential to understanding the meaning of the situation. When you put the sentence into the passive voice, the subject (i.e. Tony, the "liker") has lost most of his importance in the statement. In fact, depending on what you mean by your use of the parentheses, perhaps Tony has disappeared from the sentence altogether.
The active voice is more common and it is the usual "default" sentence structure. So when we see a sentence like this put into the passive voice it seems unnatural and contrived. Our attention is drawn to the sentence structure and it distracts from the understanding of the statement.