Call me old skool, but Legos were my favorite "toy" growing up and those sets were far more "generic". You build anything and everything, not just whatever a set was designed for... that kinda came later. Anyway, it is more fun and educational, using your imagination than it is just building a predetermined "model". I spent endless hours making stuff.
The problem was, selling bricks didn't make Lego much money. They fell on hard times because toys went electronic and the 90s were rough as everyone drifted towards computers.
They basically reinvented themselves - no kid is getting a $400 Lego set - but adults do. And adults love to collect. These sets basically brought Lego back. So while they're limited in a way, they also do sell, and licensed sets are one of their bigger revenue streams.
That said, they do make generic sets, and you can buy bulk lots, but they're more oriented towards kids who do take them apart and build more stuff with them. But they also realize there's a growing crowd of builders who want special pieces so you can order them by the brick, and a growing adult segment that wants to do a build with their kids, but have something on display.
The beauty of Lego is it can be all things. You can build this with your kid, you might then buy them a bunch of random sets for them to play with - they can choose to build the desired outcome, or who cares, open all the bags, and build whatever comes to mind. No one's touching my Enterprise, but if I give you a Mona Lisa set and you use it to make a spaceship, more power to you.
And yes, people do buy sets often to collect pieces - there are sites that value the sets on how much you get per dollar.
No one has any qualms if you choose to buy this set and build something else completely different. Or if you buy 10 of these sets to build your collection of pieces and have absolutely no intention on building a USS Millennium Falcon.