No, wrong again. The point is that your XSi CANNOT take macro shots with the kit lens. So, which is better/useful/functional/whatever the terminology you use depends on the situation. Your generalization is like saying a dump truck is better than a bus. Now that's ludicrous!
There many instances in macro product photography where you need great dof vs. shallow dof. The G11 will outperform the XSi in many of those cases. That's why it's in my portfolio. In my business there are times I could not use an XSi because it could not do the job without expensive additional equipment, where the G11 can. Do I think my G11 is a better overall camera than my 5D, 1D or D700......certainly not but it has it's place.
You know, I'm not wrong.... I actually understand what you're saying, I don't shoot with a XSi, but regardless of what I use, my argument is about capable cameras, the P&S just die at that.... a point-n-shoot, no way of making it any better, can't upgrade the lens, can't buy this L lens or that macro, zoom, wide, can't shoot 3 or better FPS, can't shoot good low light images, etc. etc..... the list can go on but I'll stop it here, it's simply enough. Yeah, you spend more on a DSLR but if your main thing is you have the ability to grow with it and having a bigger sensor size helps big time. I can see myself buying a G11 for everyday use, but I would think about using it it for high end stuff or serious work, not even as a backup camera on a wedding shoot. A XS or XSi or newer Rebel could be a great backup camera, specially with the right lens attached to it.
I really don't think the comparison is fair in any way, the G11 is a great P&S and the XSi is more than that, is actually a very good DSLR, and in the right hands you can do some amazing photography with it. If somebody wants to get into photography, I will never point them to a P&S. Now if somebody wants a decent camera to take good pictures of their kids or their trip to Europe but wants to pack light and has no plans of getting into photography, then the G11 will be a camera I would definitely recommend, I've already done this to more than one person, one ended up buying a Rebel, she wanted more controls and versatility and the other just wanted a great P&S and of course my recommendation was the G9 (G series at the time).
I don't think you're seeing my point, the bottom line, if someone like the OP asks the question as to what camera was better, even with a kit lens, I would recommend a DSLR over a P&S just for the capabilities and for the room to grow with it. I know that for some people taking great macro shots out of the box is important but the majority of people asking a question like that, don't really know for sure what they plan to do with that camera, but if you're even considering a DSLR then, for me, the choice is obvious, buy what you can that will allow you to grow unless you have no plans to get no deeper into photography than taking macro shots of a flower or a bug.