Heap (over)use by the GC is effectively a scaling factor. How large the underlying objects are remains remains relevant: if your objects are twice the size necessary, the GC will "bloat" that further - and this tradeoff isn't entirely GC specific, other allocators such as those used to implement malloc/free have related tradeoffs to make; free() won't release memory to the OS either (and memory, released or not, may end up evicted from RAM anyhow).
Of course it is relevant. I'm just saying it isn't the decisive factor that makes this an absolute necessity, as evidenced by the fact that much the backbone of the largest software services in the world is Java. There are lots and lots of tradeoffs in runtime design, and it's important to look at the whole rather than at one decision in isolation and point out that it's important. As a whole, the criticality of value types for Java is relatively recent.
