Well it's probably because of what I said earlier. YT Analytics has no idea what your revenue share is with your network. So they don't have all the data to provide the stat directly. For people with adsense, it's provided in the adsense analytics and I believe many network analytics do the same. But it's a really simple calculation: net income (after everyone's cut) / total views x 1000
Well RPM is the bottom line, figuratively and literally. Like
@Rod71 said above, RPM is the direct measure of how much money lands in your bank account for every thousand views. All the rest is just fluff.
For RPM - In the current YouTube economic climate, I'd say anything above $1 is ok. Anything above $2 is good. Anything above $3 is very good indeed. (But whether it's good or bad for someone also depends on cost of living and on how much people value their time etc.)
For CPM, as you have seen from the formula above, there are too many variables to say. CPM is just the intermediate step to RPM. A CPM of $8 could be good if the channel is getting 90% monetized views on a 100% revenue share deal. You can work it out yourself by taking your target RPM, coming up with your own revenue assumptions (% monetized views and network %) and do the reverse calculation I showed in my post above.
But honestly, it's what the CPM translates to as RPM that matters.