You forgot the most important reason why the Doctor hesitates to kill the Daleks: if he wipes them out, he takes himself off the air. :)

On a totally different, off-topic note:

I am spamming my friends list for a very good cause. Please consider linking to my post about Karen and Geoffrey, two real life friends here in St. Louis who are in great need of help right now. I can supply real names and contact information for anyone who wants to check them out and know they are for-real.

(Feel free to delete this comment if you object to its spamminess, I won't take offense.)

Thank you!