I am not suggesting any cheaper perks (that wouldn't make sense), but some evaluation of options (injection molding technique) is reasonable. Of course, I am against adding unnecessary stretch goals just for the sake of adding them, but here is my reasoning for the 'the earlier stretch goals come, the better' approach:
TOHKBD is not a common KS project. Only a narrow group (Jolla owners) can buy it and those have probably already bought it. Then there's the second group of potential Jolla buyers, but those can notice the project only in the first days, when it is featured on KS (or if there's some additional media coverage, but I haven't seen much of it yet).
Therefore if you add stretch goals after 10 days or so, there is a little target audience (it might be late already).

On the other hand, I can see that Dirk might not really need to boost the number of buyers - the goal has been reached and if not some substantial outsourcing is planned, more buyers means later delivery.

I still think some 'Thank you, we have reached the goal!' update should've happened, though (as is the habit on KS).