The main reason is that computers aren't very smart although I know that even some developers think that.

Actually they can autoland but not everywhere and then you still need to tell them where, basically tune them in on the right glide path. Then you really need to be prepared to take over any second, which is a dangerous position on its own. (Just like all self driving cars right now.)

It's still possible to select the wrong ILS beacon or entering the wrong speed or whatever, and something can still show up in front of the plane.

It's just better in low visibility where you otherwise manually have to follow the ILS 'needles'.

Didn't a plane crash there killing some chinese schoolgirls just because the pilots forgot to set the correct speed. Either it was set too low or they set it but did not activate it. And then the monitoring pilot forgot to monitor the speed since the autopilot never fails...

Raises an interesting question of which is safer: ILS automated landing with pilots on standby to take over, or pilots manually landing guided by ILS.

On one hand, a fully automated landing leaves less room for human error (you can still instruct the plane to land in the wrong place), but you're more reliant on things working as they should. If the automated systems fail for any reason, you've got pilots who are less practised at landings needing to take over at a moment's notice

I also suspect that a pilot making a active landing would react quicker to things than shouldn't happen (and thus may not be picked up by an automated system), such as a ground plane being in the wrong place, or some sort of mechanical failure.

The A320 can land itself, but pilots regularly approach and land manually to keep their manual flying skills current (as the automated systems -- both the ground components and aircraft components as well as the communications channels between them -- can fail).