They've never been a capital-intensive business, so it doesn't make great sense to invest substantial sums. Its more likely to change the business to one focused on maximizing profit, rather than improve the product.

Try the analogy where a startup is like a band (I'm not the first to use this). After the band sells out, do you expect better music? As the cliche goes, their artistic integrity is compromised, the members start in-fighting, and the lead singer grows increasingly strung-out on fame and drugs.