I did the same thing for mostly the same reasons.... I was doing 5 gal mini mash brews but now I've moved to (mostly) 2.5 gal BIAB brews.
I mostly keg, and my keg fridge only holds 3 kegs (I own 5). I was finding that I couldn't make it through one keg quick enough to move to the next.
2.5gal BIAB was a win-win-win for me.
1. I moved into all grain essentially - giving me so many more options for what I wanted to brew.
2. I found that now I can make my way through my own beer at my own time, in a normal amount of time. So now instead of saying "man, I really don't want to have ANOTHER Oktoberfest! I want to move onto that Patiersbier sitting in a keg in the closet!" I now say "Man! I can't believe that IPA went so quick - it was sooooo good!"
3. I used to buy kits from AHS and NB for the most part. Now I find myself taking 5gal all grain recipes from this site and from a few books, cutting everything in half, and brewing some amazing beer - and instead of buying my stuff from across country for 1 brew, I can drive down the street to pick up what I need. (Full Disclosure: I still buy a TON from AHS and NB, but I buy like 8 brews at a time now from them. When I'm just looking to brew something quick I pick it up locally).
4. One more nicety, it's slightly cheaper for me to do BIAB than it was for extract.
5. I get to brew more often!!!
I like brewing almost as much as I like drinking, and I LOVE having 5-10 different types of homebrew available at any given time (currently have 6 brews at some level of fermentation, 2 kegged, and bits and pieces of about 6 bottled brews).
So, in short, it's cheaper, it's more fun, I have more options, I make better beer, and I can go through it quicker!