I don't think everyone who uses the stress + consequences model agrees with you there.
Possibly not -- I can't speak to what other people think about it -- but I don't see any rules reason you would be required to take consequences to avoid a result you don't want to avoid...
And I can kind of see why. 5 complexity is enough to push through any mundane stress track, and that's not very much complexity. Seems too easy, unless you add another cost.
EDIT: Going by book examples of thaumaturgy it would be max possible defense roll + stress track + 1. So probably more like 9-13 rather than 5.
Here's how I would do actual transformations (not healing, I posted how I'd do that above).
That (defense roll + stress track +1) is just kind of a "base cost". But that only gives you a cosmetic change. If you want the change to make a mechanical difference then it's +2 complexity per refresh point of powers, and somebody (either caster or recipient) has to spend fate points for the powers as per the temporary powers rules (to avoid constant power switching effectively giving everybody modular abilities with no refresh surcharge).
Changing skills would be +2 complexity, but I don't think I'd charge a fate point since the full Beast Change power is only 1 refresh and it lets you switch back and forth.
Whether that's the best way to do it, I don't know, but it's what I would extrapolate from the rules...