All roads are now bent
Over the course of Ages, the Sea in Arda was becoming an increasingly impenetrable obstacle on the way to the Blessed Realm. Having gone the whole way from being a passable border between two continents to the realm of confusing waters and magical islands, the Sea turned into the border between two worlds within different planes of the universe.
Being places to traverse rather than to inhabit, seas separate continents and nations. They serve as a natural border and by dividing lands they also do so with cultures: traditions and customs may vary significantly on different coasts of one and the same sea. In the past travelling overseas was a thing necessary for the exchange of cultures and traditions, enriching a people’s background and, eventually, contributing to their evolution. Read more
It would be a poor life in a land where no mallorn grew.
(Fellowship of the Ring, p. 457)
While there are still Elvish realms like spots of light in Middle-earth of the Third Age, none of them is so Elvish as Lothlórien is. Legolas refers to the Golden Wood as to «the fairest of all the dwellings of my people» (Fellowship of the Ring., p. 438), which captures Lórien’s aura perfectly.