It's not a title of nobility.
It's an honorific that recognizes their service.
A title of nobility, by definition, passes through the chain of heirs on the death of the holder. That doesn't happen with honorifics.
"I have noticed in going back and watching various newsclips, that the MSM always said "Secretary Clinton", yet it was often (>51% of the time) "Former President Bush" or "Former Speaker Gingrich"."
Generally, and I mean REALLY generally, is that when you're referring to someone, instead of addressing them, you use "Former blah blah blah" if they are fully retired from public life.
In the case of Hillary, she would have been called Secretary Clinton while she was running for office. Now that she's been forcibly retired, MSNBC SHOULD be referring to her as Former Secretary...
Of course, MSNBC, being the completely unbiased news outlet that it is, has multiple sets of rules. I'm really surprised that they're not calling her Cheated President Clinton.