Eh, screw the complaints about this, I love this trope. The light is one of the few villains that actually earns the claim of arch enemies, and it makes the conflicts more complex because victory and defeats aren't a binary. The Heroes can stop the light from wreaking direct havok AND the light can still get what it wants out of it.
If anything, it's kind of a smart in terms of a genre sense sort of way. It's like the Light knows it can't get away with huge large scale destruction plans, because if they somehow did, then that would escalate their threat level and heroes would come after them way harder. But if they are just advancing in small ways, the heroes would have an easier time stopping them. So they take the "Why not both?" option where they either use the large scale destruction plans they know will be stopped as a distraction while they do the actually useful stuff, or else they just plan around the loss so that they gain some other opportunity for it.
It makes them actually difficult to stop in a more interesting way than the more straightforward planning would. The only thing that's actually lost is the viewer satisfaction of the heroes having a total victory over the bad guys, which is a small loss imo. And it makes episodes like Summit when they actually ARE all stopped in every way possible funner.
So I wholeheartedly approve of every villain being Xanatos.
