Okay... Here's my explanation:
Image link is nothing more than displaying the Augmented Reality of the world around you onto your retina. The software behind it is a simple display interface and is as smart as your monitor's hardware on your computer.
Smartlink on goggles/glasses/contacts is an UPGRADE to an image link (you can't have Smartlink without it) and has a interface with your gun's Smartgun software to display a target reticule and the gun's information onto the lenses of the item. It uses Eye-Tracking software for you to interact with the gun's operation, making it so you look at and highlight the command "eject clip" to do things like that.
This is probably about as good of an explanation as I can hope for. The eye-tracking thing is a good way to go, although I wish they would have stated it directly somewhere. Thanks.
I think of it as a comparison between, say, MS Paint (image link) and a top of the line graphic art/image manipulation/whatever program (full on smartlink). In theory and in broad concept, both do the same thing. In practice, one is light years ahead of the other.
I might find this convincing if your smartlink provided a three-dimensional battle map with a ton of predictive information and AI-enhanced advice on what to do, like a TacNet. But it doesn't- it displays a targeting reticule, shows range and ammo count, and shows the expected trajectory for a target in motion. Not only is that not anything special in the year 2070, it's not anything special now, IRL. Your image link is probably accustomed to displaying lots more complicated data than your smartlink, with fully-animated ads and the like abounding in spam zones.
Uhm...okay. So his saying that a smartlink is a an upgrade to an image link is brilliant and reasonable, my analogy that a smartlink is an upgrade to image link, using modern day examples of different tiers of a theoretically similar piece of software, isn't "convincing."
*shrugs*
Fair enough, I guess I can't win 'em all.
The part of the other poster's explanation that was convincing to me was the interface question, not the "smartlink as image link upgrade" bit. The interface thing really bothers me- with all the attention and detail they put into this aspect of the game, to simply hand-wave the issue of how smartlinks actually receive commands from the user is kinda a huge oversight.
To respond to your analogy, I feel that a more apt one would be: Your image link is like the video card in your computer. The smartlink is a little applet that lets you display on two monitors (or whatever). The video card does a million more things than the applet, even if the applet does one important thing that the card can't do on its own. My problem being, in a world where most people want to display on two monitors, there's no real reason not to build that functionality into the video card as standard, since it's well within the limits of its processing power.
One word: MONEY.
If I can get you to buy two separate things for 100$ a piece, or one, single thing that integrates the two for 150$, then I'm going to sell you two separate things.
Also, since average-joe wage-slave
doesn't want smartlink, it's not an accurate assessment to say you operate in a world where "most" people want it. It is a restricted item, by the way, you need a license (technically) to buy smartlinked glasses, you don't to buy imagelink.
Finally, when you use the book to buy piecemeal gear, do you really think you're necessarily buying it "in game" piecemeal? Perhaps, but you also might be buying the Gucci glasses with imagelink, image magnification and thermographic vision, standard. The game just hand-waves the fact that Gucci would charge you three times as much for the same product.