This makes you wish the author would have written several advanced sequels to this amazing book.
You are right that "I wish he had written ..." is preferred.
However, in informal speech, "I wish he'd have written ..." and its variants, "I wish he had have written ..." and "I wish he would have written ...", though frequently considered incorrect, happen quite often in educated people's speech (according to entry 262.2 in PEU, see below).
I found this explanation in Practical English Usage by Michael Swan,
630 wish
4 wish + that-clause: tenses
In a that-clause after wish, we generally use the same tenses as we would use, [...]. Past tenses are used with a present or future meaning.
[...]
Past perfect tenses are used for wishes about the past.
I wish you hadn't said that. (= It would be nice if you hadn't said that.)
Now she wishes she had gone to university.
In informal speech, sentences like I wish you'd have seen it sometimes occur. For similar structures with if, see 262.
Here are the relevant sections under entry 262 (for the usage of I wish you'd have ...).
262 if (7): other structures found in spoken English
2 'd have ... 'd have
In informal spoken English, if-clauses referring to the past are sometimes constructed with 'd have. This is frequently considered incorrect, but happens quite often in educated people's speech. It is not normally written.
If I'd have known, I'd have told you.
It would have been funny if she'd have recognised him.
3 had've and would've
Instead of the contracted 'd in these structures, full forms are sometimes used for emphasis or in negatives. Both had and would occur. The following are genuine examples taken from conversation.
I didn't know. But if I had've known ...
We would never have met if he hadn't have crashed into my car.
If I would've had a gun, somebody might have got hurt.
If you wouldn't have phoned her we'd never have found out what was happening.
Some explanations in this answer are going to be unorthodox, but all of them are in good faith. They are there to help you shatter your current understanding that gets in your way. (Also, keep in mind that I'm not trying to be technically precise here, but I'm more on the practical side of it.)
Let's lay the groundwork.
First, will is not the future tense. Your example sentence, Some of you will have met me before, is a good example showing why we should break away from the concept of three time zones (past, present, and future) and move toward the two-tense system (past and non-past), and why we should treat will as a modal verb, like all its friends (can, may, should, and so on). If you don't think of "future" every time you see will, it'll be easier for you to understand your example.
Second, your usage directly reflects your thoughts, your views, not situations. A typical grammar book will explain to you, we use this or that tense for a) ..., b) ..., c) ..., and by doing so, it gives the reader (a learner) the impression that in the case of a) or b) or c), we have to use that tense. Not so! This is a typical problem. The book is technically not wrong, it's true that in the case of a) or b) or c), we can use that tense. We (or most of us, the learners, anyway) arrive at the "have to" conclusion by ourselves. Most of us understand grammar backward: in this type of event, we have to use this tense, aspect, etc. Or if we find this tense, aspect, etc., in a sentence, the event must be of this type. How can we fix this? One possible way is to think of these grammar topics as "features" of a language, and they're used to give you, the listener or the reader, some clues, what and how the speaker thinks of the event. It's not necessarily identical to the actual event, but that's how the speaker thinks of it.
Third, let's consider will a little bit more. Let's consider it as a modal verb, not the "future" tense. The modal verb will can be used (according to Geoffrey N. Leech) to convey prediction (or predictability), willingness, insistence, and intention. Here are some prototypical examples:
By now they will be eating dinner. (prediction)
Will you please open the door for me? (willingness)
I will go to the dance! You can't stop me! (insistence)
I'll write tomorrow. (intention)
I think we're ready now.
Let's get back to your sentence: Some of you will have met me before.
You wonder why it wasn't Some of you (have) met me before. This suggests that you understand the simple past and the present perfect well. Indeed, both of them are grammatical, though Some of you have met me before is a better choice because it's more logical to think that the speaker is recalling indefinite experiences, hence the experiential perfect. Let's stick with Some of you have met me before because it's closer to the original, Some of you will have met me before.
If we consider will as a modal verb with four main uses (prediction, willingness, insistence, and intention), it's clear that in your example sentence, the only sensible use of this will is prediction. Paraphrasing the sentence in contrast with may have been should make this point clear:
Some of you may have met me before. (= It's possible that some of you have met me before.)
Some of you will have met me before. (= It's predictable that some of you have met me before.)
(Note that these paraphrases are only meant as understanding aids, not formal interpretations.)
I think you should be able to answer the remaining question now. Is it possible to use Some of you will have met me by tomorrow? In case you're not sure, it's Yes! :-)
Best Answer
"You'd" is a contraction that can stand in for either "you had" or "you would". The difference between the two phrases is context and timing.
If the statement is spoken before event, it can express a desire for the person to wear a suit to that event, that's the "you would" version - "I wish you would put on a suit [before we go]."
If the statement is spoken at or during an event, both versions mean the same thing. "I wish you [had] put on a suit [before we got here]."
Part of the confusion is that "put on" doesn't change spelling or pronunciation when the tense changes. If you substitute "wear", it becomes less ambiguous.
The last two statements are equally correct, but the mean of "you'd" is no longer in question.