Are you sure you're aware of how it's implemented?
In a good terminal (e.g. konsole) the text remains fully opaque while only the background becomes transparent.
This is more difficult than simply setting a window-wide opacity, which is why the terminal must have its own support for it.
So you maintain the readability benefit while still being able to see major changes to the window behind the terminal if necessary (something which I have found occasionally useful).
Yes! I never understood having transparent terminals before, but one day I discovered that configuring a slight amount of transparency, together with the blur, can be really useful. The terminal still stays clear to read.
In a good terminal (e.g. konsole) the text remains fully opaque while only the background becomes transparent.
This is more difficult than simply setting a window-wide opacity, which is why the terminal must have its own support for it.
So you maintain the readability benefit while still being able to see major changes to the window behind the terminal if necessary (something which I have found occasionally useful).