When you use the JSON format for example by executing the /tellraw command, you will notice that Minecraft decodes the complete string instead of the values for each text tag. This means you can create commands like

/tellraw @p {"text":"Click","clickEvent":{"action":"run_command","value":"/say \u02ac"}}

Chat: [Marcono1234] ʬ
Which wouldn't be possible normal because only commands in the JSON format get decoded.

Possible way of fixing it:
Minecraft should only decode the value of the text tag of JSON strings

If you remove this Mojang developers, could you please add another way to summon entities or add scoreboard objecitves with colored names instead please?