Why did Kubrick avoid a direct explanation to "Clockwork orange"'s meaning?

TL;DR:

Kubrick wanted fans who really desired its meaning to either interpret their own meaning from the film, or read Burgess' book to derive the meaning the author intended.

Long Answer:

In an article with the New Yorker, Anthony Burgess, the author of A Clockwork Orange described how the name came to him:

I first heard the expression “as queer as a clockwork orange” in a London pub before the Second World War. It is an old Cockney slang phrase, implying a queerness or madness so extreme as to subvert nature, since could any notion be more bizarre than that of a clockwork orange? The image appealed to me as something not just fantastic but obscurely meaningful, surrealistic but also obscenely real. The forced marriage of an organism to a mechanism, of a thing living, growing, sweet, juicy, to a cold dead artifact—is that solely a concept of nightmare? I discovered the relevance of this image to twentieth-century life when, in 1961, I began to write a novel about curing juvenile delinquency. I had read somewhere that it would be a good idea to liquidate the criminal impulse through aversion therapy; I was appalled. I began to work out the implications of this notion in a brief work of fiction. The title “A Clockwork Orange” was there waiting to attach itself to the book: it was the only possible name.

He also said:

I've implied an extra dimension. I've implied the junction of the organic, the lively, the sweet – in other words, life, the orange – and the mechanical, the cold, the disciplined. I've brought them together in this kind of oxymoron, this sour-sweet word.

Other explanations can be found on Wikipedia, but ultimately it's clear Anthony Burgess had a clear idea in mind as to what A Clockwork Orange actually meant.

The reason I'm bringing this up is because it is one of the reasons as to why Stanley Kubrick didn't explain the film's meaning. From an interview the director gave with Philip Strick & Penelope Houston:

S&H: How closely did you work with Anthony Burgess in adapting A Clockwork Orange for the screen?

Stanley Kubrick: I had virtually no opportunity of discussing the novel with Anthony Burgess. He phoned me one evening when was passing through London and we had a brief conversation on the telephone. It was mostly an exchange of pleasantries. On the other hand, I wasn't particularly concerned about this because in a book as brilliantly written as A Clockwork Orange one would have to be lazy not to be able to find the answers to any questions which might arise within the text of the novel itself. I think it is reasonable to say that, whatever Burgess had to say about the story was said in the book.

In other words, Kubrick adopted the attitude that people who wanted to know any deeper meaning to the story could read the excellent novel by Burgess which would explain everything the author intended.

Of course, this didn't mean he didn't chop and change what Burgess had originally written and add his own interpretations. Burgress, in a later interview, actually said:

The film made it easy for readers of the book to misunderstand what it was about, and the misunderstanding will pursue me till I die. I should not have written the book because of this danger of misinterpretation

So clearly he felt Kubrick had taken his film in a different direction (and those familiar with the novel and film can clearly see this). With these changes, new "meaning" obviously came to the film. However, Kubrick's wiki page, complete with references, shows that he always preferred to let the audience make their own mind up on his works. Film historian Alex Walker commented:

"Kubrick preferred to leave the film as the only real comment he could make on his work".

Kubrick himself said:

[He felt a film was "spoiled" for those] unfortunate enough to have read what the filmmaker "has in mind". ... I..enjoy those subtle discoveries where I wonder whether the filmmaker ... was even aware that they were in the film.

Conclusion

Kubrick often left his movies open to interpretation, hating to give any defined meaning to them. With regards to A Clockwork Orange, Kubrick wanted fans who really desired its meaning to either:

1. Interpret their own meaning from his work, or
2. Read Burgess' book to derive the meaning the author (and not Kubrick) intended.