Well as far as I know Off Peak is still SVR unless this has changed but simplification allowed SVR to be hiked to the old Business Saver rate and a new Super Off Peak ticket to be introduced at the old SVR rate. With the old system the SVR specifically could not have been increased by more than the regulated rate. The point is that I don't see how this made it simpler.
No - the fare system certainly has no been more complicated.
But NXEC did change the Saver to the Super-off peak.
If you are bored take a look at the London - Stirling fare the super-off peak is valid via Glasgow at 1630 but not Edinburgh. You will see the reason behind this London - Glasgow set by Virgin off-peak is about the same as London - Edinburgh super-off peak (set by east coast). So Virgin treat east coast priced super-off peaks with the same way as there own off-peak as they used to be savers.
If they didn't you would just split at Glasgow. But to the average traveller how are they going to know the ticket they used last week via Glasgow is not valid on a train 30 minute earlier via Edinburgh. Likewise if you get the 1430 London - Newcastle and break your journey on the return you are not allowed to use an east coast service until late in the evening but you are OK to use an XC service.