I’m guessing because it is affordable and a lot of people like the modern design; that modern design is very popular right now. Also, Sweden is the closest we have to a perfect country: extremely highly developed, high satisfaction with life, least homophobic developed country, awesome bubblegum dance music, and brightly colored furniture. Oh, and the meatballs.
I went to Ikea to get a bunch of stuff for my dorm room; it’s the perfect place for that. Not to mention the store itself is organized in such a way that it’s accommodating. There’s food there, it’s very child-friendly, it’s organized very well (showroom on top, warehouse separate from the smaller items, etc.)
Also, I really love Ikea now because that’s where I told my family I was gay. We were shopping there over Thanksgiving break at the Ikea in Emeryville and that’s where I told them. So now I’m always going to associate that with Ikea. Additionally, my mom is a big fan of Ikea, and she’s someone who loves fancy expensive furniture.
Some of the furniture they sell there is better than others, though. You have to know what to look for. I’m no expert, but my mom is always examining things up close and can easily tell which one is stronger and more durable than the other.