In the <200$ CPU range it's not uncommon to see no dedicated GPUs, both form a budget perspective and for practical perspective an iGPU comes quite in handy.
As for the productivity benchmarks the Anandtech ones put it ahead or tied with the 1600 with most benchmarks other than CBMC.
For more common productivity uses such as office work and video encoding the 8400 is faster, sure it won't beat the 1600 in Cinebench but how many people render in Cinema 4D on a sub 200$ CPU? And even in Cinema4D MC it's not that far behind.
At this point it's really not a "no-brainer" it's about price, if you aren't going for a dGPU the 1600/1600X might not be worth the premium unless the initial shortage of CoffeeLake is going to hike the price above the 180$ MSRP.
If you are buying a dGPU and will be gaming it's again not a non-brainer since the 8400 is faster, although at that point paying 70$ more for the 8600K and pushing it to 5-5.2ghz would be much better.
If you are looking to build an SFF PC or a NUC again the 1600 is not a non-brainer since you will need to account for a dGPU.
At best you can say is that the 1600/1600X are still competitive, but they are quite far from being a non-brainer.
In fact they are only competitive because of the recent price cuts, if the 1600X was still priced at $250-260 the only non-brainer here would be the 8600K.