Why Rock Band, Guitar Hero and DDR Extreme are not brought back?

they never came BC due to the peripherals not being compatible with Xbox one and newer, also releasing new ones costs money, song licences are very expensive and the popularity of those games was falling near the end of the 360 era, so the game would have been expensive to make and licence all the music for and with the uncertainty of sales, means the end.

You would have to ask the developers and publishers of those games that question. The only one on Xbox One/Series X|S is Rock Band 4. The older games are not backward compatible because they need the Xbox 360 peripheral (guitar, Drums etc, etc). Also, the 360 backward compatible program has now ended, and no more of those games are to be made compatible.

If you would like new versions of those games for current gen consoles, then contact the developer and publishers about it.

Fender Stratocaster (RockBand) is compatible with Rock Band yet is not compatible with Guitar Hero II Guitar Hero III: Legends of Rock

why? rock band is dead and guitar hero iirc is gone as well. there will probably be a rock band on next gen consoles but that's it they don't need rock band from X person because no one cares anymore.

Aren't the Stones already in Rock Band/Guitar Hero?