There have been ten Trek movies, and I'd say that two of them are accessible to mainstream audiences, another two are great, and the remaining six are nearly unwatchable.
Obviously, the four movies he's talking about here are 2, 4, 6 & 8.
I'm not entirely sure if the two "mainstream" movies he's referring to were 2 & 4 or 4 & 8, as the Borg in First Contact were updated with an entirely new look and a ton of special effects that made it appealing to a wider audience.
While I wouldn't go so far as to say the other 6 were "unwatchable," I think it's important to note that, with the exception of IV, the ones that are good all had something in common that the other six did not.
With the exception of 4, 2, 6 and 8 ALL relate back to something that had happened previously in Trek lore. None of them tried to reinvent the wheel, but rather follow up on a pre-existing story.
Every attempt to create Trek from scratch has been the "tower of suck" that he worries this movie could be.
1, 5, 7, 9 & 10 all tried to tell stand alone stories that the casual observer could follow without really knowing a whole lot about Trek history.
Abrams is trying to buck this trend and create a from scratch story that makes Trek "better" than it's been previously and more accepting to mainstream fans and general audiences.
Sorry, but I simply don't see it working.
Further, as a Star Wars fan, I wonder if Abrams would be one of the first to stand up and cheer or jeer anybody but Lucas who'd come along and try to do with that franchise what he's attempting to do with this one.