I think the ideal of eternally sealed marraiges needs to be articulated AND "embodied" - to be accepted "publicly" as an open statement of intent. There's a degree of that in "'til death do us part" (since it articulates staying together until the end in many people's eyes) - but I really want the ideal to be forever. Symbolizing that eternal commitment truly to start with a distinct "two" and become an inseperable "one" means a lot to me, and I think it should be "embodied" in an actual, physical, participatory ordinance / ceremony. Therefore, I absolutely love temple sealings.
Personal opinion time:
Is there anything magic or automatic in it? Absolutely not.
When it comes down to it, will it make a bad marriage good or a decent marirage excellent, in and of itself?
Will it automatically make two become one? Absolutely not.
Will the lack thereof keep two who truly have become one through life from continuing as one after death?
So, why bother?
Ideals should be taught and embodied in symbolic action as much as possible, imo - since that really does mean something to the vast majority of those involved, and since there truly is great Beauty and Power in such an ideal. I believe in that ideal deeply and passionately, and having a way to make it "tangible" and "recorded in my soul" means a lot to me.