Benefit of playing this Ko variation in 4-4 6-3 enclosure?

[shoryuu]

http://josekipedia.com/#path:pdttqfqcpcpbobrb

$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 6 . 5 . |
$$ | . . . . . . . . . . . . . O . . 1 . . |
$$ | . . . , . . . . . . , . . . . O 2 3 . |
$$ | . . . . . . . . . . . . . . . . . 4 . |
$$

Click Here To Show Diagram Code

[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 6 . 5 . |
$$ | . . . . . . . . . . . . . O . . 1 . . |
$$ | . . . , . . . . . . , . . . . O 2 3 . |
$$ | . . . . . . . . . . . . . . . . . 4 . |
$$[/go]

Any reason why the top diagram is still played when the corner can be locally killed with no Ko when the more common variation below doesn't allow any immediate direct placement to kill?

$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . 7 . |
$$ | . . . . . . . . . . . . . O 4 3 1 . 9 |
$$ | . . . , . . . . . . , . . . . O 2 5 8 |
$$ | . . . . . . . . . . . . . . . . . 6 . |
$$

Click Here To Show Diagram Code

[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . 7 . |
$$ | . . . . . . . . . . . . . O 4 3 1 . 9 |
$$ | . . . , . . . . . . , . . . . O 2 5 8 |
$$ | . . . . . . . . . . . . . . . . . 6 . |
$$[/go]

B doesn't have to care if surroundings aren't strong enough here to run out. As long as he wins the Ko, he lives.

[Uberdude]

How do you kill the top if Black pushes at q17?

[shoryuu]

P18. Then depending on the surroundings, it could die. But the point being made is that there is no Ko and you HAVE to run for that variation so I don't see any upsides.
You get 1 less option of Ko.
If the outside was already that weak then is it to perhaps lure the opponent into playing the placement to try to kill so you can destroy the outside?

[Uberdude]

After p18 I cut at r15.

[baduk]

Hello,you are right,if white is strong enough she can kill,but in most cases you cant,the variation without pushing has the advantage of beeing lighter,so if black is not confident to have enough tjreats he will choose the variation with no push,because its not that risky