This probably sounds very cynical, but IMO record companies capitalise on the burst of (free) publicity generated by the death of someone young and charismatic. It gives them a window of time in which to get the product recognised and build a market. There will be a limited amount of product for sale even though they are prepared to scrape the bottom of the barrel in terms of unreleased material. Being in business, they need to turn their investment in the artist into profits.
On the other hand I'm sure that the people who worked with, befriended and developed the young talent will be desperate to see that their work doesn't disappear unnoticed.
BTW Lisa Lopez was surely already a big thing with TLC.