I still have access to all the bags in my inventory. There are two tabs, furniture is the default tab and you have to select inventory to see your bags. At least that's how has always worked for me.
ETA: ACK! I reloaded and now I have no bag access in decorating mode. This is really not cool, I hope this is temporary.
My inventory tab was missing in decoration mode, too. I was wondering if this is a glitch or a purposeful change. Either way, I don't really mind, but it adds an extra step to putting things in my attic. :(
I experimented and dragging something down to your inventory brings up bag access. Likewise, dragging furniture brings back furniture access. Seems really a lot more clumsy than tabs. I'm assuming this is just temporary.