Using this definition there are, on average, 237,345,536,820,000,000,000 aborted blocks every 10 minutes at the current difficulty. Eliminating these would eliminate the concept of proof-of-work and would eliminate the consensus mechanism built into bitcoin. How would you make that work?
How many were there in the first year of Bitcoin, and how many will there be in 5 years time? You don't have to eliminate all of them, just make block creation more efficient.
There is an incentive structure built into bitcoin so that mining is always exactly as efficient as it needs to be.
As more energy efficient hardware is created, miners have an incentive to use the more efficient equipment since it will reduce their electricity costs. Therefore, hash power will move to the more efficient hardware, so mining is more efficient.
If the exchange rate drops, then mining isn't as profitable. The most inefficient miners shut off their equipment and the difficulty is reduced. Less hashes are needed, so mining is more efficient.
If the block reward is reduced, then mining isn't as profitable. The most inefficient miners shut off their equipment and the difficulty is reduced. Less hashes are needed, so mining is more efficient.
If the exchange rate increases, then the network is more valuable and needs more security. With the increased revenue less efficient miners can afford to run hashing equipment and difficulty is increased. Mining becomes a bit more inefficient to increase security.
If transactions pay higher fees, then the users value the network more. With the increased revenue less efficient miners can afford to run hashing equipment and difficulty is increased. Mining becomes a bit more inefficient to increase security.
This incentive structure is balanced so that the exchange rate determines how much hashing is needed, and the amount of hashing determines how expensive it is to attack the network, and the cost of attacking establishes the security of the blockchain, and the security of the blockchain contributes to its perceived value, and the perceived value drives demand, and demand determines the exchange rate and with that we are back to the beginning.
As such, more efficient mining overall (less "wasted" hashes") means a less secure blockchain. So, before you can decide how many "wasted" hashes are acceptable, you first need to decide how much security is desired.