As to why we need trading cards and smiley in Unicode, the reason is pretty simple: compatibility. The goal is to be able to convert all existing text data into Unicode, this is why DOS area block drawing are defined as codepoints. Emoji were added to add compatibility to the Japanese systems so that companies like Apple could enter that market with the iPhone, without this, iPhone users would not have been able to exchange messages with other users.
Remember that at one point in time, ASCII was the extended character set with unnecessary symbols like curly braces, this is why C++ compilers still have trigraph support
If prices of ISBN codes were really a problem, people could just publish in France, where ISBNs are free. Anyways nowadays ISBN are just a particular class of GTIN/EAN so I suspect one could just buy an EAN (UPC) code.
If we hit the reset button, can we also fix ASCII? it is by no mean the minimal set most english speakers think it is.
Why do we need a character to represent to 'v' one after the other? You could write 'w' with to 'v' and handle the ligature where it should be handled, at display time. There are so few words in English with the sequence vv that it makes no sense to have the special case coded in the encoding.
Also could we handle the dots on the characters 'i' and 'j' like the diacriticals they are? there should be first the the dotless 'i' and 'j' and the some character to add the dots, like all other diacriticals. Also move out the currency symbols ($ and £), they can be represented as text (USD and GBP), no point in have silly symbols in there. Also remove BELL (11), having a symbol for a bell (2407) might be bloated, but having one for the sound of a bell is absurd.
By the way, why do we need different code points for upper and lower case? They are just variants of each other anyways
Unicode is certainly messy, but plain ASCII is not much better: the most precious 127 code points of utf-8 are basically wasted to display 32 characters and a bit of punctuation, that is pretty bloated for me, we are just used to it
Or turn the problem around: if one provider of telecom services is ever condemned without any other proof than the fact they benefit from a hack, the bad guy just change their business model to extortion.
"I may be synthetic, but I'm not stupid" -- the artificial person, from _Aliens_