I actually agree with this 100%, I just remember blowing through the whole game one day and just being like "that's it? wow, okay"
I honestly couldn't tell if it was just because I'm so used to the modern lego game formula or what, but I just didn't enjoy it at all.
This is 100% incorrect, destroyed with facts and knowledge, because of one thing:
The level creator (which was technically first in Lego Harry Potter 1-4 but we don't talk about that).
If this had just been "another lego game", this arguably would have been the worst. The levels really didn't stand out much at all compared to its predecessor (which I still haven't played, RIP), and the open worlds were weak at best. However, that implies that this was the main focus of the game, which it clearly wasn't.
I cannot tell you the countless hours I spent on this thing because it was so absurdly fun to mess around with. THIS embodied the heart of lego more than any other game I could play at the time, because you could just make stuff up. Stories, characters, everything. It was amazing. It was a standout feature that put it up there with innovators like Lego Batman 2 (which honestly hasn't aged well in light of its successors but oh well) and Lego Star Wars 3.
Maybe that's just me though.
I'm also glad that I'm not the only one who wants a remake of lego battles, that game was awesome.