My kids do the same - they ask for Lego Minecraft sets or Lego Ninjago sets or whatever, build them and stick them on the shelf. They’re horrified by my suggestion that they tear them down and build other random things with the bits. And, of course, a lot of the bits nowadays are so specialized that they have limited uses. When I was a kid most of my lego was just standard blocks.
I was a K’Nex kid more than a LEGO kid, but I remember both my K’Nex and LEGO sets coming with manuals that had directions for making dozens of things, all from the same set. That shit was awesome, and was a really good way to teach you the creativity and skills to go off script and make your own creations. Buying a LEGO set intended to make one specific thing seems counter to the original purpose of the toy.