Yes, we all love what we are doing. And yes, we really love to share that with others. It is too easy to get frustrated with those who either don't understand our dedication to pursuing a specific avenue of interest or just frustrated over the fact that not everyone even cares that specifics even exist.
I do, however, firmly believe that Generic Garb has it's place in the SCA. Imagine there is a new member to the society who thinks they want to do a Middle Eastern persona but are not really sure. Or perhaps this person is an SCA veteran whose talents do not lay in the field of research or even sewing but they want to go to a Middle Eastern or Viking themed event. Maybe this individual does not know much about the culture, but really want to make an effort to be a part of the theme (and thereby add to the event's over all atmosphere). They likely don't have time to look further into the details (or maybe they just are not sure which specifics they want to pursue) so they opt for a generic look that not only meets the SCA's Attempt rule, but exceeds it by at least trying to better fit into an event. Either of these people are great candidates for Generic Garb!
As long as that generic-viking is not telling anyone else that what they produced is the one right way to do it, more power too them. And, honestly, they might just like it enough to want to go a step further the next time. I also find that often individuals are even very happy to engage in conversations with specialists who might have useful information to make their look even more period. It is all in the way the matter is approached. Additionally, I think its important that those who choose to specialize keep in mind that not everyone wants too go down that road and it is really quite OK if someone does not care to discuss the fine points of period and place appropriate Viking brooches.
So yes, I do teach "Generic Garb" classes on occasion (and am preparing to instruct on Viking aprondress construction soon, hopefully). And based on the feedback I got, I think the classes I have done were well received and I know that my Middle Easter Coat class/handout got quite a few people stirred up about learning more about period Middle Eastern garb! (As soon as my I have a chance to revise my handout for that one, I will post it here.)
So yes, generic garb has its place and I certainly hope that people to enjoy what they have made enough to explore the details further!