Well, I don't know what version of NVDA you last tried to use, but it definitely can announce this kind of things. Yes, it does have to be turned on (or off in a few cases, respectively), but I personally see that as an advantage. I wouldn't like to be cluttered by all the possible formatting info being announced all at once by default.
It does tell you when you start or stop typing in italics and bolt respectively, and when reading and browsing the text, it can either announce the formatting changes automatically if configured to do so, which might cause some lag which is either more or less prominent depending on your system, etc, or the announcement can be triggered manually with the designated keystroe at the exact moment when it's convenient to you.
Lukas