Well yes, you downgraded. If you downgrade, you lose features, you don't gain them. There has never been a standard dual monitor taskbar for windows 7. There were apps that did it for you, but those were unreliable.
It actually make more sense the way the dual (or triple) monitor works in 10. In 10 I was able to set the main screen, w/ Start AND Tray on the center of the triple. That was not easy in 7. Having the Start and Task Icons on all screens in 10 is helpful as well...
Well yes, you downgraded. If you downgrade, you lose features, you don't gain them. There has never been a standard dual monitor taskbar for windows 7. There were apps that did it for you, but those were unreliable.