Because sometimes you can drop words without running the risk of being confusing, often because the context fills in the blanks.

For example, if I write something and John responds "That's interesting. Would love to talk to you further about it" -- it's not made explicit who would love to talk, but who else than John could it possibly be? If on the other hand John's reply reads more like: "I liked your post, and my friend Steve found it particularly interesting. Would love to talk you you further" -- in this case you risk being confusing, because would John or Steve like to talk to you?

There's a similar effect with a sentence like: "That's an interesting observation. Might be good to get some more data." You've shortened "It might be good...", but that's OK since there is no risk of confusion.