You both bring up good points. Raj, you're right about them being made that way to make them easier to fit into, because of the stretch. What I was trying to warn you of was them not necessarily changing size much differently over time. However, what Phukette said is also an important factor that I had forgotten about. Different stretch jeans may use different stretch fabrics which act differently. For those, with the lyocell, I'm not sure which way it will go.
Ultimately, your opinion of them and the look is what it all comes down to.