Plus keyboards now have pitchwheels and mod wheels so they can imitate the sliding of the finger on the fret etc. And also , BASS is not like acoustic guitar where one of the beautiful things about the guitar is you hear the WEEP sound when the fingers slide to create new chords or slide a finger to a note... IN BAS you don't really need that.

So why not just use Keyboards for BASS sound?

Some sounds, can only be done with a Bass Guitar.
Seinfeld?

Hi, cozoDOP2!

There are many nuances in sound and effect, that can only be achieved by the use of a finger or fingers plucking a string. Playing a key or keys, no matter how many devices are built into the keyboard, are still no duplication for that which can be achieved by a person actually playing an electric or acoustic bass.

Furthermore, in playing an electric or an acoustic bass for many different types of music, there are a lot more effects that can be achieved than those that you've already mentioned.

I'm a professional bass player.

Thanks!

The bass is also much simpler to learn than the piano(keyboard). And as Clough mentioned some tone can only be done on an electric bass