You can only afford to run Java on an embedded system when you are making limited-run devices, i.e. where the cost of the processor & RAM etc are negligible.

For most embedded devices, this is not true.

When you're paying for every device the code runs on... and that code wastes 80% of your cycles in abstractions and indirections then forces you to have 200% more RAM than the equivalent C code, that changes your mind.

Saving a tiny amount on a processor adds up when the multiplier is (say) 1 million units.