People are acting like crossplay (in the long term including huge third-party titles, not just with Minecraft), is a huge win for every consumer - but that's ignoring the fact that most gamers already in the ecosystem have preferences.
For me, personally, I've invested and spent thousands on the PS4 ecosystem. Because of that, and because I want Sony and its studios to continue the type of production they've shown throughout the PS4 era, I want Sony as a business to be healthy. As a consumer of PS4 games, mostly, it's in my best interest for Sony to not make choices that could negatively impact business. It's just like buying a stock.
There are certainly advantages to universal cross-play, sure - higher player pools, connecting with friends etc. - but I feel like a lot of people are focusing on hypothetical benefits (everybody in my office wants to play Game X after work!) as opposed to real-world scenarios here. Personally, approaching 30, most of my friends from the 360 era have just quit gaming. I've made new friends on PSN. I'm also fine playing against (or with) random people from matchmaking. It's just really not that big of a factor for a lot of people.
The thing is, though, universal cross-play has massive ramifications for the industry. Doesn't anyone find it a bit suspicious that Microsoft is banging the cross-play drum just as we're approaching a holiday season where they're set to launch a new console that will, according to them, give you the best experience for all multi-platform releases? Wouldn't you want to be able to boast, as Microsoft, that you can deliver the best experience *and* you don't have to abandon your friends? Buying an X1X would be, for many, a no brainer. Microsoft isn't doing this because it wants to make you happy, it's just as much a business strategy as Sony's denial of crossplay.