I really don't have the best memory, but I believe every Mojangster except Jens who showed up at PAX this year was originally a modder hired by Mojang & given a cushy job in Sweden.
I definitely appreciate modders, especially the one who makes obscure low-demand mods like "long hair for men" & for women like me who have unusual fetishes, because who else will thank them? I remember my favorite Morrowind Mods...Done by Cait (I think), whom added spawning sand dollars, hermit crabs, seashells, starfish, seaweed, coral, birds, deer, horses, cats, dogs, squirrels, rabbits...All the little things developers overlook for cost & time reasons. Now if I could just find a mod in any game that made the land near water look wet.