It's like @FXRich said...just because you have a car that'll go 150 mph doesn't mean you have to drive it 150 mph. The same holds true for mods and tanks that go well over 100 watts. Just because a mod will fire down to .01 Ω doesn't mean you have to run a .01 Ω coil. Just because a mod will go up to 200 or 300 watts doesn't mean you have to use that mod's full potential, which is ultimately the point - potential. I like the fact that I can run 120 to 150 watts with my Cloud Beasts and I like the fact that I'll be able to push a King Beast up over 250 watts if I want to cloud up my mancave. At the same time, I like the fact that I can build a 1.8 Ω coil in my LEMO or my Kayfun and run it in the neighborhood of 15-20 watts on the exact same mod if I just want to chill and do some MTL vaping.
Options and potential. That's the point of being able to run a mod over 200 watts.