In the mid-1980’s the Pennsylvania Avenue Development Corporation and five developers who were building residences required under The Pennsylvania Avenue Plan as part of mixed-use developments began meeting to see what everyone could do to make the area atractive so that people who had not lived here in any numbers for a century would want to do so again.
They coined the word Penn Quarter since in Washington, DC, every residential neighborhood seemed to have for gain a name, just for the reasons you mentioned.
For example, in the 1950’s a study (I may be wrong, but I think it was undertaken by the National Capital Planning Commission) to determine if a neighborhood warrented some sort of designation was suddenly renamed. That neighborhood had two elementary schools named Adams and Morgan. You know the rest!
Another example is how the area north of Mass. Ave. came to be called NoMa from an off the cuff remark at a meeting in reference to the triangle of land between NY and Mass avenues east of Mt. Vernon Square. Somehow those with land in that area liked the name Mt. Vernon Square East beter and NoMa was too good to throw away so some people attached it instead to a no-man’s-land a bit further east as there were no other possible names for that spot on the map.