This is a great change! It really helps to go all-in.
If the 33% weekly reinforcements stop, then it won't matter the strength - it'll go down eventually just like old incursions.Well two of them were populated so it would be nice to give them back to humanity. Plus some people might not want the remnants hanging around in case they start growing again.
Meanwhile if clearing Titans doesn't weaken the systems around them and clearing the systems around the Titan does nothing to make it weaker, then the point is what exactly?