There is no obvious structural purpose to have that painted strip...
It's just an accent to show the different roofline/window profile of the Targa.
Completely uneccessary as a design feature, the targa's much sharper final window was different enough before to differentiate it and make it very easy to tell from the side profile...
It's obvious that it will divide people's opinions, but porsche knows this, there will still be many people in this market, otherwise there would not have been this model at all in the 997 line up (as was long rumoured).
The new chassis's rigidity shouldn't be that compromised, (as with the 996 - it's based on the coupe chassis and not the weaker/heavier cab chassis in the 993).
Mabye we'll even see a wider range of targa models, Turbo targa anyone ?