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.
you don't want to spend 10 of your 15 minute break making coffee with the aeropress. I have one and it makes fantastic espresso but it's a giant pain in the ass to get one cup out of (to be fair I have never tried pre-ground beans I use a hand grinder with it so that might change this calculus).
I haven't used it in years when I go camping I buy instant espresso instead. Only tastes 80% as good but it's 90% less effort, mess, space used up etc.
I interpret your mention of pre-ground beans as an item that is bought, but if you need fresh coffee on the go you can just pre-grind them for yourself and take them with you.
I personally have an electric coffee grinder so my pour over is done in about five minutes, then I let it cool and take it with me in a thermos. Though I also only drink 1, max 2 coffees a day.
When I was using mine in office I used the little bags of pre-ground. But I also enjoyed the routine of making the coffee and explaining it to any curious onlookers.
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.