The simple answer is that the costliness and wastefulness of the process is the precise reason we use that process. If someone were to discover a technique that made mining easy and efficient, this would actually "break" Bitcoin, and a patch would be required that re-introduced costliness to the process.

This is because mining is the act of adding new transactions to the existing chain of all previous transactions, making a bigger longer chain. If building up this chain were easy, then people could make their own chains and try to trick the network to accept them as the real chain, changing the record of transactions. But since it is very costly to build up a chain, if you tried to make a competing chain, your chain would look puny, and weak and fake, next to the big, meaty, real chain that included millions of dollars of "wasted" proof of work.