I think his point is there are tradeoffs, and I agree. On top of that, meaningful debate over what tool should be about what context you're in. This applies to the OP's slidedeck.

To give context about my comment about context:

* was nagios setup before you started the job?

* did you setup nagios yourself?

* is your internal process for managing nagios broken?

* culturally do you work at a place where ops is an afterthought?

* if Nagios is your technical debt do you have a way out? are you crushed by other commitments? Maybe it's more of a management/culture issue.

... hmm actually I should stop. From re-reading your comment, I can't tell how much of it is trolling (in a entertaining Skip Bayless, right wing radio, Jim Cramer kind of way).