Instant coffee is nasty for those who appreciate REAL coffee, i.e. brewed or french press.
Regarding use of brewed coffee on shabbos, if you use the Melitta pour over cup, or the fantastic invention called the AeroPress, you might be able to use them on shabbos with a ‘klei revii’. I spoke to my rav and he explained to me how i can use it on shabbos.
No more nasty shabbos morning instant coffees! Now that’s true oneg shabbos!