Why do some trees produce cones and some not?

There is a kind of pine whose cone holds onto the seeds inside it until it is exposed to the kind of heat that would result from a forest fire, then it releases its seeds, which will then do well, because they will have lots of sunlight in the clearing that results from a burned-out forest, and the seeds will also derive valuable nutrients from the ashes of the fire. In some species, the cones are a more or less accidental aspect of the evolutionary path of that particular tree. Even though organisms evolve toward efficiency in filling a particular niche, there are also many aspects of evolution which are simply accidental.

All conifers produce cones. All other trees produce their seed by other means.