Most of those negative comments are made out of gross arrogance or gross ignorance.
All microcontroller products started life on some type of development board. Whether that board is Arduino or ATmel is of little significance.
I totally agree, I don't see why an expensive development kit would be any more or less capable unless it's spec'd differently for the needs (which can't be simply decided upon just because you want to offer a hardware development kit). The problem is the perception, whether right or wrong, with the team I've spoken to is that Arduino is an 'amateur' platform for 'small prototype projects', whereas a more 'enterprise' development kit would somehow get them to market quicker with higher quality product.
I can somehow understand their argument, but only if the architecture of the final product is required
to be significantly different than an arduino-based prototype, but since AT chips are presumably used in all manor of embedded devices, who's to know if for instance an energy meter is based on AT or Intel as long as the thing does it's job.
Arduino is a development board with low overhead
Precisely why I'd love them to offer it as an option for developers... I'd love to see the 'entry fee' for the development platform get lower and see how much more innovation is done with it.