I agree, Lego are really expensive but I know compared to the knock offs, they are much better quality, and hold much better. I saw my nephews playing with the knock offs recently, when he showed me what he made, I picked it up and a chunk fell off!!!
I had a lot of joy browsing in the store on this occasion, and like you, I found that quite satisfying as I wasn't going to buy anything anyway.
I have watched people reviewing Legos. The joy, for adults, seems to be the process of building those large stuff, like a guy was super happy building a Millenium Falcon (Star Wars) on youtube for hours.
That just made me realize I am grown up and don't really have the time, but I can dream to have it someday (both time and money).