I have not read all the responses, very intentionally; I want to give an uninfluenced opinion.
I am a SAHM. I decided that as soon as I was able, I would not work. I just couldn't stand the idea of not being there once my first was born, before that I had planned on being a working mom. That doesn't mean I will always be a SAHM, I tend to look ahead and keep my resume up. You never know what the world will bring that might require me going back to work.
However, my kids all go to preschool even though I am home. And I swear it is the best thing I have done for them. They love it. They love what they do there. They love being with other kids. And all the teachers are great, especially the ones we have had. It has been good for them on so many levels. Socially. Seperating from me. Learning different routines. Preparing them for school. It's just great. Not to mention, all I can get done. Laundry. Clean house (I tend to spend my time with the kids when they are home--which is the majority of the time--rather than dusting, it's not going anywhere and the kids are growing up). Run errands. Doctors appointments. Grown-up conversation with a friend so I don't totally loose my identity.
So, do I think it is wrong? Absolutely not. One, they like it. Two, they are getting something important from it. Three, productive, happy parents is also good for them. Four, it could be more upsetting to change their routine.
If you know what you are doing is right for your family; do not even consider allowing anyone to second guess you. There are all sorts of different ways to do things--home schooling, public school, private school. Music or Art lessons. Baseball or basketball. Bottled water or Tap. Point is, it can get a little silly. Truly, I believe those that feel that you are totally "wrong", really need to justify to themselves that they are making good decision/filled with self-doubt. I mean not were not talking about anything that is black and white like murder...