I find it would be more practical, for it if this were to become a community, it could indeed, as you say, make more difficult for someone who generally interested in wide variety of writing utensils to see drops. But that problem would be simple enough to resolve for said person would just have to subscribe to the newly formed community (also newly formed communities are mentioned in emails and on the hub page).
But on the other hand, if you were to take a person who main interest was indeed calligraphy, then the creation of this new community would make it much easier to see drops that concerned that field only. I, per example, don't have a major interest in so to say 'regular' pens, yet from my notifications that is practically all I see, and scarcely little calligraphy related drops.
Also, if the community happened, then it undoubtedly would encourage massdrop to feature more calligraphy drops then they currently propose, or so I'd like to think.