First, the number of projects still on 8 is low, and almost all of them are legacy projects with little to no evolution.

Second, modules' encapsulation is not what caused the migration difficulties from 8 to 9+, evidenced by the fact that it wasn't even turned on until JDK 16: https://openjdk.org/jeps/396. From JDK 9 through 15, all access remained the same as it was in 8. The reason a lot of stuff broke was the JDK 9 was the largest release ever, and it began changing internals after some years of stagnation. Many JDK 8 libraries had used those internals and had become dependent on them not changing - though there was no promise of backward compatibility - because there was no encapsulation.

Finally, the market clearly wants things like projects Loom and Panama and Valhalla, things that wouldn't have been possible without encapsulation (at least not without breaking programs that depend on internals over and over). It's like people complaining about the noise and dust that installing cable ducts causes and say, "nobody asked for this, we just asked for fast internet!"