.we lose the stand alone nature of childs
A child theme isn't standalone by definition. It requires that the parent also be installed.
its a short step from there to omit the step and hack the default i guess
I think you might be missing the point of child themes. If you make your customisations in a child, you can happily upgrade the parent without over-writing your custom templates/functions/CSS. so you can have all the benefits that a parent upgrade might bring in terms of extra functionality without having to re-customise from scratch again.
in fact what u propose is worse that hacking the default because if u run a lot of sites yr upgrade path is really ugly
I'm sorry but that's simply not true. I can build a parent theme and install it on 20 different sites - each with their own custom child theme. If I then want to add extra functionality to every site (for example, add 3.1 post format support), I simply need to edit a single theme (the parent) and upgrade that single theme each site instead of upgrading 20 different themes.
Having originally had about 14-15 free themes available for download on my sites, I can assure you that keeping them up up-to-date with the latest WordPress functionality was a major chore. So much so, that I'm gradually retiring them in favour of only a couple of child-aware parent themes and associated child themes as, and when, needed. It makes my life a lot easier and means that I can get parent upgrades out far more quickly with each WordPress release.
the notion of child themes can only take root if the parent is sufficiently robust eg more action hooks
I wouldn't necessarily say that more action hooks are needed - although I'd dearly love to see a de-register hook similar to that available for plugins on deletion. I do think that parent themes need to be built with child themes in mind - otherwise building the child can become an exercise in frustration. Plenty of filters and nice modular functions seems the best approach, in my opinion. But you never really know how well you've implemented this until people start building child themes. Which is one of the reasons that my latest theme has recently been released as a beta - so that people can try it out and feedback any issues.