Clearly that team would have some free throw issues, but it's worth at least noting:
Smith is 65% for his career, Howard is 58%. They may not improve, but there is certainly precedent for returning to your career average. Those numbers aren't good, but they aren't awful for two big men. Getting the opponent in foul trouble consistently helps, too. There's a reason why Shaq's career wasn't derailed by FT shooting. Those guys more than make up for missing 10% more free throws on the defensive end.
This is not to say I particularly want to pay the max for either of them, but I think we would manage the free throw issue. We could easily have 3 or 4 guys in the rotation shooting 80%+ from the line and reap the other benefits of our big man talent.