The thought behind wattages as high as 200W is future-proofing and mass appeal. You don't have to use it at 200W, but if you do vape that hot, then you'll be able to. Using wire with a really high heat capacity might require 200W. Maybe you like to use 18AWG and vape quad coils. 50W per coil for 18AWG seems feasible to me if you like that kind of vape. Even with the 22AWG dual-coil builds I normally do, I vape between 60W and 100W. Add 2 more coils to that, and I'd need between 120W and 200W to get the same heat.
It was the same argument when 50W mods started getting mass-produced. "Why would you ever need 50W!?" And now we have cloud-chaser tanks that work up to 100W, maybe a little bit more...and you don't even need to build a coil.
It may seem excessive now, but who knows? Maybe in 12 months, we'll have premade quad-coil heads that require higher power. If you're going to release a DNA+10W every year, why NOT go for broke and make 200W an option? Then just release firmware upgrades and ride it out long-term. Then you have a board literally anybody can use...low wattage, high wattage, low resistance, kanthal, nickel, temp control...I mean, is there anybody out there right now that legitimately thinks that they can't vape the way that they want on a DNA200? I would genuinely like to hear from them if there is such a person out there.