I get your reasoning, I guess it's a matter of point of view. To me, making earlier episodes, rather than prequels, seems rather pointless. Why even show the earlier exploits of Anakin if you're not going to show him turn to the dark side and become Vader? That's the whole reason why the films were made, really.

It makes sense to view the films in order of release, and see the use of "Episode" as an indication of chronology and the release order as a clever conceit to hide certain facts.

I don't know how anybody could watch ESB (the first film to have "Episode" in the title and also the film with the big surprise) and not think "oh, Episode V, I wonder what happened in the three episodes before Star Wars," and then, when Vader reveals his true identity, think "oh my god, that must be what happens in those three episodes, Luke's father becomes Vader!"

Ultimately this is my biggest issue. Why have a prequel trilogy, why follows these characters if not to learn exactly what happened before the OT? Are you sure you want to watch a six film saga where one of (if not the most) central character has a life altering transformation practically offscreen?

All I know is if ROTS skipped the birth of Vader I would have been royally pissed off.