A number of things, I think, are true...
To begin with, we see what Lebron's tendencies are: on-ball, all the time. If he ever learned, or had a coach that might make him learn, how to play off the ball, he could be an unstoppable weapon. That means that I sincerely doubt he would ever willingly be a low-post option. He won't wait for the ball. I used to think it was that Mike Brown was a turrible coach (he is), but Lebron needs someone to coach him and hold him accountable for implementing a team-level strategy.
Bosh is who he's been all along. While a 3rd banana on offense, has he stepped it up by focusing more on defense or rebounding? I don't think so. That's on him, but also on a coach not being clear with expectations. It seems they're going with the "we've got so much talent, we can just work out a groove" thing, but that won't cut it in the playoffs for sure. Chicago (with Booz) might beat them.
Surely the perimeter/slashing oriented game of Wade and Lebron is redundant, but lacking an inside force is killing them on both sides of the ball. Many players/combinations of players could improve/balance out this team. Heck, Troy Murphy would be an upgrade to Bosh. Robin Lopez and Dragic would seriously put them over the top. Bosh just doesn't add enough of what they need.
Actually, if Miami had signed David Lee, Amare, or Boozer, I would be much more worried about facing them. Darko/Love for Bosh-type deal would make them not only contenders, but favorites, IMO.
This Heat team may know a lot about basketball, but they don't know anything about winning on the big stage. Riley stepping in would be something I would be very concerned about, too.