You put the problem with your idea on the table your self. You can verify or you can Trust. The words we use are 'Do not Trust, verify'. Your idea goes against that particular fundamental value of Bitcoin.
We have pruned or full Nodes. We have SPV. The Blockchain or Bitcoin itself does not need a change to accommodate the people who want to cheap out on time and space to add Trust instead. It is not worth while. You could get a 2 Terrabytes used Hard Disk for as little as 30 to 50 Dollars. I would not recommend it but if you want to cheap out on something, any consequence should be on you. Not on every body else and on Bitcoin itself too. There already are a couple risks Bitcoin has to pass. For example the 51 percent attacks. Adding Trust would be just another risk and it is even pointless too.
You’re very correct chief, I guess most folks are familiar with the phrase “Don’t trust, verify “ and this phrase has been the mantra on which Bitcoin security stands and that is why users can independently verify transactions and blockchain state without the requirement of trusting a third party. so when folks start to introduce shortcuts that require them trusting someone else, then the very guarantees that make bitcoin robust will be undermined and that’s why SPV exists as a compromise because it allows lighter clients to operate without fully storing the blockchain and thus in turn reduces resource burden like time and storage while still minimizing trust, whereas , introducing shortcuts that are trust based would make users skip verification entirely and rely on someone else and that goes against the bitcoin principle because it re-introduces trust which bitcoin was specifically designed to eliminate.
