can somebody explain to me why?
For me it's the same, the pleasure and freedom of being able to design something that doesn't necessarily have many straight lines in it. It's a bonus that you can make 2 or 3 in a similar time as it takes to make one (make one, sell one, give one away). My machine has only been running a couple of weeks, and isn't truly finished, but I'm loving CNC so far - if you can imagine it, you can make it!

So perhaps you can answer another question which follows on from that, namely "Which CAD?" AutoCAD is a good commercial product but hopelessly over-priced for hobby use. Whis is the most popular CAD/CAM amongst the users of this forum? Is there such a thing as a concensus?
My workflow at the moment is ProgeCAD Smart -> Cambam plus (still in my 40 trial startups) -> EMC2. This is fine for 2D and 2.5D cutting. The programs import and export via DXF.
ProgeCAD Smart is basically the same as autocad, and free for non-commercial use. http://www.progesoft.com/en/smart-2009

Later I'm going to get more into 3D forms (I have a very specific project to make a wedding present for some good friends), and have started to learn Blender (a pretty steep curve). Again export via DXF, but I haven't tested Cambam like this yet...

I don't know about a consensus though! :)

In summary, if you need to find some critical views on CNC, you probably need to try a different forum!!