Because virtual pictures are not always replacements for actually seeing/touching/weighing/measuring/sampling tissue firsthand.

LOL kay!  Love that your questioning child is 35 - it's a great question! 

I don't have any indicators of how often autopsies are done these days - but here are my impressions from working in health care -  it's virtually 100% if its a forensic case - for purposes of evidence collection.  In most cases where someone is in hospital, and a diagnosis is evident and death is anticipated, I don't think an autopsy is usually done, since cause of death is known - but I can't say for sure.   But when a patient unexpectedly dies, one might be sought.    Or if the case is unusal, the illness rare, and there is mecial/scientific learning that can be accomplished via the autopsy, then sometimes one is done - that usually involves both gross & microscopic examination of tissues etc. as Gord mentions above.   I'm not sure what's involved if a person who is ill dies at home - I would imagine similar to if they die in hospital, providing there are no suspicious circumstances.   Hmmm ... I don't think I really answered your specific question very well ...

 I think autopsy's are done as much to take samples and to really look at organs.  An image is just an image.  Weights, sizes, colour and samples are important.

All unexpected deaths may be autopsied, despite objections.  Not all will be.

Any deah in hospital within 24 hours of admittance same.  And suspicious death or unknown origin

And then really any that the cornorner wants to take another look at.

 some things can only be found out by using a microscope too.

Imaging doesn't always give a good picture- and also is likely more expensive than autopsy. My son had an MRI of his injured knee, which I believe took over 20 pictures. Now picture this for the whole body.

Often, the surgeons don't know the extend of a tumor and metastases until they cut a person open.

scanners like an MRI don't pick up colours, just textures and sizes. 

a lot of information regarding cause of death comes from the colour of the tissues, and examination of fluids within the various organs. 

I have no idea, Kay...but laughed when I read your opening sentence about your child...hahaha, it's true...we always see them as children.