I wouldn't call it "Brand Dilution" but rather table-top-RPG-game dilution.
Yes, you (or others, like myself) might think of D&D and table-top RPG to be synonymous (just like "Xerox" and "copy machine" or "kleenex" and "tissues") but they are in fact separate. All that is happening is that the tabletop RPG market is getting more recognizable products/brand names that are gaining larger portions of the market share than before when D&D had the lion's share.
A brand dilution might better describe it if WotC was supporting two editions of D&D at the same time, or something like that -- where the term "D&D" was representing more than one product at a time. I can't think of any examples at the moment, but, realistically, an example of that would probably be hard to come by since it wouldn't be a very good practical business decision.
Yes, you (or others, like myself) might think of D&D and table-top RPG to be synonymous (just like "Xerox" and "copy machine" or "kleenex" and "tissues") but they are in fact separate. All that is happening is that the tabletop RPG market is getting more recognizable products/brand names that are gaining larger portions of the market share than before when D&D had the lion's share.
A brand dilution might better describe it if WotC was supporting two editions of D&D at the same time, or something like that -- where the term "D&D" was representing more than one product at a time. I can't think of any examples at the moment, but, realistically, an example of that would probably be hard to come by since it wouldn't be a very good practical business decision.