Yes, I can see that logic in terms of a 22+ episode series and the requirement of a single storyarc running through it. How to maintain the story interest and what protagonist could credibly last that distance where The Flash is concerned other than a fellow Speedster...?
I think a flaw in the series is that it has set itself up as a heroes vs Supervillains formula, when what it should be doing as a season is aiming for more character based storyarcs set on exploring a given character mystery and how it eventually resolves itself, big flashy Supervillains like Reverse-Flash and Zoom don't have to be the formula if you were to focus more on exploring the cast and setting a trajectory and endpoint for them wach season.
I don't know if I fully agree. At this point in time they should be EXPERTS on how to stop a speedster. Heck since Barry is a speedster, the first thing that should have been created was a device to stop a speedster (in case Barry ever went rogue. BESIDES a cold gun).
I think a fleshed out Mirror Master or Abracadabra (or any magician based) villain could carry over for 22+ episodes. Even a Ra's Al Ghul or Lex Luthor type character could work: the metas would be the henchman, but there would be a non-meta mastermind pulling all the strings.
C'mob writers, Flash has been published for HOW many years. Certainly his rogues contain more than speedsters. Worst case scenario, take a page from the Arrow book and use somebody else's villains. lol