Maybe, but they don't currently give each app its own IP, and might not want the complications of volatile IP reassignments, DNS TTLs, and so on. (Though, their current "CNAME-to-yourapp.herokuapp.com" recommendation would allow for this.)

...want Heroku to do the icky difficult stuff...

Yes, but to a point. Customers also want Heroku to provide a simple model that allows scaling as easy as twisting a knob to deploy more dynos, or move to a higher-resourced plan. Customers accept some limitations to fit that model.

Maybe Heroku has a good reason for thin, fast, stateless routing -- and that works well for most customers, perhaps with some app adjustments. Then, coaxing customers to fit that model, rather than rely on any sort of 'smart' routing that would be overkill for most, is the right path.

We'll know a lot more when they post their "in-depth technical review" Friday.