I had another thought on this...
If you truly, deeply love and respect and care about someone, isn't it cruel to enter into an agreement with them that takes away their option to change as life changes? You also forfeight the choice to change your life, if you so feel fit, at a later date. Why would anyone choose such a situation for someone they profess so much love and respect for?
This is my biggest criticism of the marriage institution, and why divorce happens so frequently; PEOPLE CHANGE!
if marriage is about emotions and ensuring that personal fulfillment is met, then you have very good points. if marriage is about commitment and stability and pooling of resources and child rearing, then what you have written above might take a back seat (it ain't about you anymore, it's about the functioning of the new unit/family.. a third body that is not subject to being dismantled because of your personal wants and needs). Some of this is about a culture of individualistic narcissism.
also, I'm sure over the course of my life I will change in many ways, as might Tim. That doesn't mean we won't work, actually the more space we allow each other on our own personal journey's, the closer that may bring us. Having said that, our vows don't include any time frames and our marital contract only includes our intentions.
I do agree, given the level of consciousness at which most people make lifetime commitments, coupled with easy escapes (i.e. "I know deep down that even if I say this, I don't really have to mean it, I can get a divorce"), and our attitude that marriage is about emotional partnering and ensuring personal fulfillment... given all that...lifetime promises are highly unrealistic. Most people can't even commit to quit smoking, or to stop eating potato chips, or getting to the gym... but they're willing to promise a lifetime of fidelity and love?