"in itself" should be synonymous to "per se,..."
Agreed, "per se" and "in itself" have the same meaning. However...
...so I think of "in and of itself" as a more explicit way of expressing a direct relationship. And because usually the phrase is used in a negative context, less is negated when something is "
not X, in and of itself."
For example, something could be "X, in itself," but also "not X, in
and of itself."
Heads will hurt.
This doesn't really make any sense to me. Firstly, I disagree that "in and of itself" is used generally in a negative situation vs. "in itself". I've seen it used in both circumstances.
The use of "in and of itself" is still not markedly distinguished from the use of "in itself" or even "per se" (however, the general use of per se in a sentence's structure varies from the previous two, which are interchangeable). Let's look at a couple examples (bad with examples, sorry) of swapping out these terms and note that the meaning of the sentence, or for that matter the tone, does not change.
The weather was not, in and of itself, the cause of the traffic delays
The weather was not, in itself, the cause of the traffic delays.
That, in and of itself, can be a shock
That, in itself, can be a shock.
I don't think I've ever heard someone say "in and of itself" on here or anywhere IRL. It's probably considered nonstandard English, like using paparazzi as a singular word instead of a plural (the proper singular is paparazzo). I use nonstandard English quite a bit when I'm talking with my friends.
Being Australian also, it's not a phrase I have ever encountered with another Aussie, written or spoken. However, pay attention and you will see it used in this forum and definitely in writing on other websites. It's not excessively used, but it's one of those things that once I paid attention to its use (as I'm not a fan of it), I started to notice it a lot more.