dissolve in cold water, ONLY THEN add hot water. The rationale behind it is that aromatics evaporate too quickly when the instant powder is infused with too/boiling hot water.
I imagine there are tons of office workers, mechanics, construction workers, etc. who are drinking instant because it's impractical or impossible to have a coffee machine at work or in the field. I believe the vast majority of coffee vending machines also use instant coffee behind the scenes, so everyone who's ever gotten a cup of highway rest stop coffee was most likely drinking instant at least once. Ditto with the "cappuccino" machines at every convenience store and gas station on earth.
I carry instant coffee with me when I'm camping, because I can't be bothered to have to carry and more importantly clean any kind of coffee gadget.
I've seen 'em and I've used them in the past. They're a fine solution, but they still require cleaning and a couple of satchels of Taster's Choice or whatever is easier on the KP and also much smaller than a giant coffee syringe. Showing up at the pay-for-pitch in the station wagon is one thing, but usually all my stuff needs to either fit in my panniers or my backback.
There are guys I've hiked with who have them, though. To each their own.
I just brew in my French press after dinner, pour some into a thermos after it's done, and store the rest in my French press in my fridge. The next day, I pour more into my thermos. I feel even old coffee tastes better than instant, but I understand that's my opinion.