You just aren't getting it. Do you actually know Chinese, or are you just looking things up in a dictionary?
It is pretty natural to jump from 喜 to 囍 because that is how Chinese works. You take radicals, and you bundle them up. You have the "busho" system where people in the past bundled up little bits and pieces and form new words. No reason why people in the present can't do the same.
Re: Micro$oft being outrageous if $ becomes a part of the alphabet. You are misapplying an English oriented viewpoint. In Chinese, there is no objection to forming words in that way, by incorporating radicals together. It's similar in theme to how in German, you can just keep stringing words together to form larger words. In fact, I actually think in the future, words like Micro$oft should entitle $ to become part of the alphabet! That's a very Chinese way of looking at things.
Language is not static. Systems that try to encode language are descriptive. They can never be prescriptive - otherwise we as a civilization die.
If 囍 wants to be a character point, let it be one. If 福倒 wants to be one, there should be one. Isn't the point of unicode to have enough space to include all these kinds of language artifacts (artifact as in a cultural / historical item thought up by humans) in order so people can uniquely reference each one? They are distinct logical units.
If the unicode rulebooks are too rigid, the rules need to change or the approach needs to change. It's useless to try to argue that xyz character in another language shouldn't/can't be a character - people will just stop using unicode if it doesn't suit their needs.
Reeks of colonialism, that's what it is.
EDIT: as an additional gloss, here's why I think 喜 and 囍 are sometimes used differently, even though by the dictionary definition they seem to be the same. I will explain why I think logically they are different concepts.
喜 is happiness, delight, joy. It is probably an adjective in the English sense (I can't map grammar rules through different languages easily).
事 is an occurrence, an item, something that happens.
When you put them together,
喜事 literally means something happy is happening.
The cultural meaning has turned that into a connotation of "wedding", but it could actually be a ton of happy things. Promotions, and yes - one other really big thing in a person's life: having a baby.
有喜 (means "having happiness") is the traditional way of referring to a woman being pregnant
http://baike.baidu.com/view/301829.htm
You can turn that into 家有喜事 - meaning home having something happy - as in this household is having a baby. And you can use it without the 有 - and just use 喜事 to refer to having a baby.
This is different from a wedding.
囍 is a modification of 喜, by doubling up the character and treating it as a radical, people are referring to the idea that there are "two people having happiness" - like a doubled amount of happiness.
In the article linked http://www.chinatimes.com/newspapers/20160623000760-260115 - the 囍事 is used to specifically identify the "wedding" type of 喜事 - it's like trying to avoid the ambiguity and double-entendres that Chinese writing typically embraces and just presents things matter of fact, which is ideal because the article is a newspaper article about customs of towns. Not really something you want people to have multiple interpretations like an essay or a poem, for example.
So logically, there is a difference when trying to use 喜 vs 囍 and I actually really appreciate the author's use of the double version in the text.
I know that not everyone reads these characters in this way, but I do - and I'm sure other people will notice this too. It's the best part of Chinese - not knowing, and not seeing the ambiguity, and one day, someone tells you about it .. and you're like - OMG that's what that means ...
For my earlier indication that this type of character modification is common in chinese:
木 = wood
林 = common last name Lin, also means forest (uncommon on its own)
森 = common character for forest.
The English word "forest" is usually 森林
It's just a doubling and trippling of the 木 radical.
What does it matter that this character is super old - people thousands of years ago thought this up.
Also, if this character weren't so old, would you say that 森 and 林 are both forests and thus don't need separate character points in unicode? That's outrageous!
So now we have a modern version of this modification 喜 -> 囍
And I showed how I think they are different logical concepts.
The link http://www.chinatimes.com/newspapers/20160623000760-260115 showed how it can be used in typographical context.
hmm what's the issue with it being a unicode character point?
POST Edit
In the writing of this post, I think I've come to identify Chinese as an "ambiguity-first" language - I learned Chinese as my mother tongue, but stopped at a elementary school level, and switch over to learning English to a Bachelor's degree level.
In Chinese, puns, double-entendres, and ambiguity just "happens" by default, and you have to work your way to be crystal clear.
English is more straight-forward, with a speaker having to try to make puns or double-entendres.
In the case of 囍, it's a reduction in scope. Modern Chinese people had to create a new word just to narrow down the meaning of 喜 - so that it specifically refers to weddings.
Your whole line of thinking was that 喜 already had meanings inclusive of wedding, so 囍 can't possibly add any more meaning when it also means wedding. In actuality, it took away a bunch of extraneous connotations, and in Chinese, the reduction in complexity is so valuable that it's worth a new word.
I think that it's a mistake to try to over-literate and reduce languages into a set of rulebooks for character encoding - that's all I am trying to put forth - it's best for the person or peoples who speak the language to come up with the encoding for it. I have an elementary school knowledge of Chinese and already I am kinda miffed at why people have an objection to 喜 vs 囍
Imagine how the people who have Bachelor's degrees in Chinese must feel.