AVRFreaks.net

There's been a lot of talk about ARM taking over the embedded world, but the reality is that there is still a hefty chasm between 8-bit applications and entry level M0 devices like the xxx chips, and it goes beyond SW or MCU cores. Many low-cost products where 8-bit dominates are still assembled by hand or via wave-soldering with packages like TSSOP or DIP, whereas (with some rare exceptions like the DIP xxx) ARM has largely been confined to more modern, machine-placeable packages like QFN, QFP or BGA. Price has also been an issue, even with the $1 xxx chips breaking new ground at the time of their release (though they're still an impressive value today!), but those rules definately change with the $0.39 xxx chips in very familiar DIP and TSSOP packages.

This is a rationale for DIP packages