As it becomes available on more blogs, some blog owners have decided that it's actions are not to their liking, and would like to return to the old, manual moderation process.
The basic system, of having comments moderated using a collaborative and heuristic filter, will affect all blogs.
This is intentional, and cannot be avoided.
We really think it makes sense to have the comment spam filter an integral, non-optional part of Blogger (think Gmail).
It is to everybody's benefit that we all work together, and jointly identify what comments are spam - and which comments are not spam.
If you find that some valid comments are being placed in your Spam folder, or that some spam comments are being published to your blog, because you have not moderated these comments, you will need to start moderating. You have to moderate, so the new system knows which comments you consider to be spam, and which comments you consider to be valid.
If you are happy with the initial placement of comments - into Published, or Spam - you are entitled to disable moderation for your blog. You can, optionally, still disable moderation for newer posts, and select the threshold for disabling moderation. But when you disable moderation, your blog will still be subject to automatic placement of posts - into the Published state, or the Spam folder - as decided by other blog owners.
The new filters will work much better, if everyone participates. Use of the new filters simply cannot be an individual choice - everybody has to use them. Decide for yourself, whether you wish to actively participate in moderation, or whether you will let others moderate for you.
Blogger does want your feedback about the new system, in a Forum Discussion thread. They do request that you make your comments and questions productive, and spend less time asking how to disable the new system.