In the four-man dialogue that constitutes “An Essay on Dramatic Poesie,” the author Dryden is represented by the character of Neander. Right throughout the dialogue, he shows a willingness to depart from current rules and standards in relation to the composition of drama and poetry.
Among other things, this means that in the battle between Ancients and Moderns, which excited so many of England's foremost men of letters at the time, Dryden, in the form of Neander, is firmly on the side of the latter.
That's not to say that he doesn't have time for the Ancients. On the contrary, he very much respects them. It's simply that he regards modern works as superior, as they are much closer to ordinary life than the somewhat elevated productions of classical theater, with their strict rhymes and their adherence to Aristotle's three unities.
For Neander, the violation of the three unities allows modern drama to escape from what he sees as the straight-jacket of classical theater. As modern drama is freed from the rigid interpretation of Aristotle's rules, it is more creative than its traditional counterpart. What's more, it is much closer to life, not least because it doesn't need to be written in rhyme. The language of modern drama is closer to the language that ordinary people speak in their daily lives.
Although Pope greatly respected Dryden, and certainly learned a lot from him, his whole aesthetic outlook was radically different from that of Neander. As a consummate neoclassicist, he was a firm believer in following rules when it came to dramatic and poetic composition. His own poems display this fidelity to long-established rules of composition, with their regular meters and their heroic rhyming couplets.
In contradiction to Neander, Pope was also of the belief that the Ancients were superior to the Moderns. In keeping with other writers of the neoclassical movement, he believed that the best art emerged from imitating the example of the ancients, whose own works displayed an insight into what was universal, timeless, and of enduring value. In emulating the great writers of the past, Pope strove to be part of a long and noble tradition. As such, he was somewhat suspicious of the kind of innovations recommended by Dryden and put into the mouth of Neander.