Does that kinda throw off the whole concept about pushing language design if you can't do coroutines?

That's a pretty critical feature of Lua that somewhat defines it(along with it's low overhead + embeddability, both of with you won't get with the JVM).

It seems like engineers always want to build One Tool to Solve Them All(tm) and yet there are always tradeoffs to be made. The reason 90% of this industry is still employed is because we don't have these one size fits all problems that we'd so love to solve.