First of all I wouldn't characterise it as a ban - the reality is that the ruling that "legalised" it wasn't right since the supreme court was usurping power from the individual states that have democratically elected leglislatures therefore it was undemocratic.
The whole point of the US system is that each state is semi-autonomous so federal power is restricted to small number of areas of policy - e.g. defence or cross state crime etc. For stuff such as murder (for example) federal government has no involvement) and the local people through their elected representatives get to make those laws. Why did they treat abortion differently in the 70s? Well because surprise, surprise not everyone agrees that abortion is a good thing and the folks in federal government wanted to get their way despite what many people in those states actually wanted.
To me (and many won't agree I'm sure, but that is allowed), all human life has to be respected and supported where possible. It doesn't make sense to say that this life matters and that one doesn't - as soon as you do that you are opening the argument up to weigh up other lives - look what happened in Germany in the 1930s/40s when they used similar arguments to say that some lives are less valuable than others. I see these arguments today to support legalisation of post-natal abortions - I see that as evil. I do have sympathy with plight for women who have been made pregnant against their will or through error but short of a circumstance where the life of the woman is in danger I don't see that as a compelling argument. I do think the state should support such women though - e.g. through accomodation/financial support etc and the penalties for men doing this should be higher - they need to have consequences too, in times gone past it was a shotgun marriage but that has fallen out of favour now.
An analogy could be that imagine a person (A) finds themselves on the side of a bridge holding on to another person (B) dangling over the side. A is physically strong and B is very small so A has no problem holding onto B. B is unable to climb to safety by themselves. A can sustain B's weight for considerable period until help arrives or A is able to pull B to safety. If B falls they will certainly die.
In this situation A could let go of B and go about their business - would this be "right"? It would possibly be legal (I guess it would be a big legal argument) but would it be morally right?
I think most reasonable people would say that A should either pull B to safety or hold B until help arrives.
