Atmel is so visible though, no wonder they're getting gobbled up. From a hobbyist point of view, I see so many projects involving Atmel chips is almost makes me think they have a monopoly on that, growing, segment of the market. This probably has as much to do with cheaper cost as it does with (relative) ease of use.
Isn't it more that Arduino boards dominate the hobbyist microcontroller space, and they have historically used AVR? IIRC, most new Arduino models are now ARM based.
There are even some MIPS ones like the Yun which use Atheros SoCs.