I don't see what's wrong with IKEA's layout. I mean, it's bad if you came there to buy a particular something (though in that case, you can just skip the gallery section entirely and go straight to the well-organized shop and warehouse sections.) But it's exactly right for what I go there for: looking through the gallery as a 1:1-scale-model catalog, deciding what you want/need from that browsing, and then picking it up if you still want it by the time you see it again in the shop section. It's destination shopping, in the same way a bookstore is.
I hate Ikea for this reason. The last time I went, I was looking for a bathroom vanity/sink. By the time I found them, I was so annoyed at being forced to navigate the serpentine displays that I walked out. Yes, there are cut-throughs, but they aren't labelled. Time is too valuable to be wasted walking around furniture I don't want or need.
If you went there alone, then you're not really the target customer.
Most customers come to Ikea with family or spouse. The store's design provides a space of reflection on the state of their own home against an unfolding sequence of idealized Scandinavian nuclear families. At the end of the pilgrimage, ample opportunity is provided to make amends with cheap impulse purchases.
To me it's irritating when I know what I want and don't want to browse all day. I may want to see the qualities of an item upfront but I don't want to go thru the rest of the maze to get to the warehouse to pick out my items.
But it seems to work for most of their shoppers due to a combination of price and utility.
They have discreet shortcuts for if you do know where you're going. It's very cleverly designed so that the "natural" path through the store takes you on the grand tour, but you can get straight to specific places if you need to.
In my IKEA (in Edinburgh), there's a shortcut from the front entrance meaning that to get to the warehouse, you only need to go through Cooking & Eating, Home Decoration and Home Organisation to get to the warehouse, skipping almost the entirety of the store. You may want to check your local store's map on the IKEA website.
And this is why we shop ikea backwards... walk in the warehouse door, pick up a coffee, find the thing in the catalogue, and skip the showroom altogether.
Unless you're doing it because you enjoy the coffee, you can just find the right thing on the website, reserve it, walk in and pick it up. They do support that kind of workflow if that's what you want.
For some businesses it works because they offer enough to overcome the inconvenience while others do it out of incompetence or simply cargo cult.