[jsharpe]

If you're interested in making and finishing a game, there is no good argument to be made for writing your own engine unless you have some very very specific rendering requirements (e.g. you want your game to be in hyperbolic space or something, or have 3D portals).

In every other case by writing your own engine you'll be wasting your time on a million already solved problems instead of actually, you know, making a game.

If you're interested in game engine development, or graphics programming, and not so much in finished games, then you can write some engine code as an educational exercise, though.