It's not necessarily much less repugnant. The fact that rich people can spend their time doing whatever they want, while a lot of people have to burn themselves out working two jobs to make ends meet, is abhorrent. However, the ability to make ends meet through selling your organs is a line most societies haven't crossed, and I'd prefer to keep it that way to be honest.

And for better or worse, we do tend to see a difference between forcing people to sell their time and forcing people to "sell their body". It's one (among many) reasons why societies tend to look down on prostitution, for example. Prostitution, like paid organ donation, is the kind of thing that I see no issue with people doing voluntarily, but I take issue with systems which "force" people to do it out of desperation.

I think society would be better if we started viewing the selling of one's time more like we currently view the "selling of one's body". I think society would be worse if we started viewing the selling of one's organs more like we currently view the selling of one's time. We want people to labour in order to keep society going, just like we want people to donate kidneys to help people in need, but we don't want an unfair division of labour where an underclass is working 80 hours per week while an upper class has all the free time they could wish for, and we don't want an unfair division of kidney donations where an underclass feels forced to donate their kidneys while the rest of society never even has to think about it.

Yes, I think it is that. Any such "time for cash" arrangement will have an end date, and can be terminated or renewed regularly. Whereas selling a kidney - once it's gone, it's gone. The transaction can't be repeated.