Now that video/audio capability is in all Nikon DSLRs, why is it that you can still only record a voice comment on an image with the Pro bodies (D4, D3,etc.)? It seems like it would be easy to implement now that the hardware is built into the cameras.
I've always found this to be a handy feature when shooting with a manual lens when I want a record of the settings, or some other note about the photo.
Feature differentiation and likely price-point. While it may be technically trivial to add, it may do so at a cost that would drive the lower-end bodies price-points up. At the low end of a product line, you're in the weeds trying to get the nickels and dimes and make your product still somewhat profitable and competitive. Think also about the use model - if you took a survey of non-enthusiast users (i.e., the real target audience) how many of them would want or care about a feature? Would they care about it's inclusion if it affected the price?
"Hard to see why there would be a cost- the video bodies already have a mic built in, and the firmware has been long done- cut and paste from the D3/D4?"
If only firmware deltas were as simple as CTRL-C/CTRL-V. Actually, firmware might be hardware limited - you may have a headspace issue loading the image, and every line of code counts. Cost savings could extend all the way down to the chip level - so lower-tier bodies gets hardware A which costs 20 bucks. D800 and Dx series gets hardware B which costs 70 bucks. B would be able to handle a bigger firmware image and have a few more bits and bobs that makes changes easier. That's just an example, I have no breakdown on actual costs.
I wish there was a website like iFixit that would do a cost component teardown of every major DSLR and compact camera out there, but that's a pretty expensive process to inform/satisfy only a minority of users.
I also think it's price/feature differentiation, and nothing more. That being said, while I have the feature, I find it clunky and continue to use an app on my iPhone for the purpose of recording some quick comments about my images while shooting. It's called PhotoJot.