It's less to do with the tennis and more to do with the fact that Dimitrov is "marketable", particularly now that he is one half of a "glamour couple".
The thing is that it becomes a circular argument. People want to watch him because they've heard he's the next big thing, and the commentators tell everyone he's the next big thing who everyone is interested in. There was a moment at the final at Queens when the commentators were falling over themselves to say what a great guy he was, apparently because he was holding hands with the young player from the Baltacha Academy. A few seconds later Lopez did the same and it didn't get a mention. I'm not sure they even noticed.
Obviously, I understand he's good looking, has an attractive game and going out with a tabloid favourite, so clearly there will be a lot of deserved praise. I just wish it weren't at the expense of his peers. I don't think it's particularly important that Dimitrov has achieved little compare with Andy/Novak/Rafa at the equivalent age, because times have changed, and they need to inject some enthusiasm about the next generation. IMO, it should be spread out a bit.
Earlier on today's coverage they did a segment about all of the up and coming young women in the game, and I found it really interesting to see them compared with each other and how they were all steadily progressing up the rankings. As far as I'm aware they've not done anything similar with the young men, but have spent much longer raving about just Dimitrov.