Not meeting with the POTUS certainly isn't going to help the CBC get their issues better or more inclusion/consideration in regulatory and legislative matters than they might have otherwise obtained. It's, however, not likely they were going to get any of them considered to begin with. Thus, I'm hard pressed to see them gaining or losing, from a governance standpoint, by not meeting with Trump.
I can see them as losing by meeting with him. It's not so much that they'd lose something specific because as I said, they weren't ever for the whole of the Trump Presidency to get anything they want anyway. Had they met with him, they would have provided Trump with an political strategy and optics opportunity to cast the meeting as someting it was not, whereafter the CBC members would have been carrying-on to refute the POTUS', who has the best "bully pulpit" in the world, representation. That'd have just be another "he said-she said" distraction.
I don't think anyone wants more of that, and people who do can get on All My Children. The Trump Presidency and Administration, lo Trump himself, is already "too much for 'daytime' television." It's probably best that the CBC didn't give him more fodder for promulgating even more drama.