First, things like TVs. Not only can you actually see tvs plugged in and how they look, but you can also get open boxed ones to save a few bucks.
Keyboards and mice. You're not gonna be able to get a complete, full experience like when you're sitting down to really use it, but you can get a pretty damn good understanding of how it feels.
More good products from the actual brands, instead of hundreds of scams or cheap Chinese products that will break in a month being drop shipped. I wouldn't be able to count how many times I've seen the same exact product show up multiple times with a different company name. It's one of the reasons I try to not use the vast majority of online shopping sites. Having an open market sounds awesome. You get to sell your own stuff and reach a wider audience. But people are greedy fucks and ruin it for everyone.
Also, I sometimes like going to stores. It's an excuse to get out of the house. It doesn't feel like it fills that need when I'm grocery shopping, but if I'm gonna go buy something I want, then it makes it more exciting. If I got nothing else planned for the weekend, might as well.
The only problem is that I only have BB for electronics. So the options are a bit limited.