Mash Tun vs. BIB

I'll post this to the BIB and All-Grain forums as well, but...

With Brew-in-a-Bag methods these days, is there any real "advantage" or "benefit" to doing more "traditional" all-grain brewing techniques for most beer recipes???  Can't the same things be achieved via BIAB???  As a beginner, BIAB seems really easy, and I'm wondering why I "should" spend more money on buying/building mash tuns, and other equipment.

Thanks for the opinions/input.

My limited understanding would point out efficiency.  How much of the sugars are you extracting and how much is left behind in the grain?  And is that important to you?

To be honest I have gotten rid of everything to downsize to BIB. I have my whort circulating continually through the entire process. All of my gravity readings have been spot on. However I do soak for 90 min. Also if you think your efficiency will be reduced increase your grain and soak times.  If you play with it a little you will find what you are looking for.

I'm an idiot...I use both processes together...Gets the most out of the grains and then the bag makes it easy to remove grains from the GOTT... Works pretty well and i get every speck of sugar out of my grains!
But again, glutton for punishment/idiot...