I always got the impression, similarly to you, that Sony let their devs do their thing. Most creatives want to move on, eventually. Nobody wants to be known for just one thing and never evolve. Naughty Dog, as an example, moved on from Jak because they wanted to try something new. I like to think Sony MOSTLY respects the creators enough to not want to disrespect the IP.
And seriously, there's something of value to be said about knowing when it's time to move on. Uncharted is a great franchise but I'm happy to see them move on. I'd be completely satisfied if 4/Lost Legacy was the end of that franchise. I'm also happy if Bloodborne doesn't get a sequel. Not everything needs to be Franchised.
I tend to assume that most decisions companies make are based on profits rather than respect or integrity.