I don't know, maybe it's how he consistently, easily wrote in iambic pentameter, a meter which is fucking hard to achieve? Maybe it's the way he had all tragedies, comedies, and histories, all almost effortlessly rolled out? Maybe it's that his characters have development throughout the span of the usual few acts? Maybe it's the well developed use of dramatic irony, allowing characters misfortunes to be predicted, in that "Ohhhh, he's gonna get it!" kind of way? Maybe it's that the man was an absolutely unparalleled wordsmith, putting to ink for the first time hundreds of words that are commonplace today that were never before seen in literature, such as Bubble, Critic, Addiction, Outbreak, Leapfrog, Mountaineer, dialogue, dislocate, torture, unmitigated, assassination, and worthless.
Oh, no, wait, it's all of those things combined! Silly me, forgetting something like that. And yeah, he's not the best, and the gods alone know what happened to the ending of Love's Labor's Lost, but he is pretty damn good when you can understand exactly what he's writing, which, judging from your lack of knowledge of most of his works, I would say is something you don't do.