[Comments] aren’t a utility to propel your blog to a state of maturity where you finally shed [them] in a burst of enlightenment. They have intrinsic value.

I think you really hit it on the head here. I think it's isolationist a little bit to shut off your comments and invite readers but not invite their opinions. Sure, controlling spam and bots is important, but going radio-silence is, imo, not the best way to start the conversation.

I also think it's a little selfish to turn off your comments. Just as Facebook sells you to their advertisers in return for you using a free service, I'd argue you should have the opportunity to opine after reading somebody's blog.