As said above…
There are several 3rd party planes that haven’t updated to natively use the G1000NXi. The marketplace mod forces those planes to use it instead of the old, stock G1000.
Same deal with the GNS package. Currently, only a handful of Microsoft planes will natively use the new GNS. Others will use the default GNS. This mod forces them to the new GNS until those planes are updated to use the new WT GNS natively.
So whether or not you need those mods installed totally depends upon what planes you fly. But it’s likely just better to leave them installed until such time they’re no longer needed.