1). Assuming that we all trust your assessment that 10 minutes is an optimal interval between creating new block.
No one said it's optimal. Without any other empirical data, however, it's
good enough. It gets the job done. The interval could surely be lower but no one knows how much. Nine minutes? Eight minutes? We don't know. Bitcoin is in alpha development and security has to come first. The Bitcoin network, today, moves
more than two billion dollars per hour (see
here). We can be quite sure that 10 minutes is enough because propagation delay for unobstructed light around the planet is about 7-8 seconds. That means that there is enough time for almost 100 network-wide updates before the next block is due to arrive. The probability that the network could not reach consensus in this time is virtually zero. And that's precisely where we want it to be - virtually zero.
As someone has mentioned here before, it wouldn't be a bad idea for us to plot out the chart and analyze to see what the best blockchain interval should be .?
That will be a great PhD project in 10-20 years' time: "Minimizing Bitcoin block time based on empirical evaluation of mean network-wide time-to-consensus."
I'm still leaning how to use the bitcoin core full node, once I'm getting familiar of my way around, I could definitely doing some data analysis...perhaps, 5 or 3 minutes could be more sufficient ?..
Or perhaps 5 seconds or 3 seconds or 8 minutes or 7.5 minutes. Without data generated from reproducible experiments, it's anybody's guess.
2). As I indicated before, just because we could hash at 1 second it doesn't mean we have to confirm the block right away..? What about if we create a build-in a time delay on the off chain/ second layer (e.g. the Lightning Network, which acting as a "trafiffic cops") , let say if it's less than 5 minutes then put in a counter to count up to a fixed interval..? I also have heard that the bitcoin core code doesn't like to use loops for the obvious reason...Look, I'm not a software developer, but I'm an automation engineer, I believe there are options that we all need to explore before we quickly shut all the doors and declare that it's impossible to address the problem...
As more technical people joining this community, we will continue to hear voices raise regarding how wasteful the hashrate and the difficulty levels are being used on bitcoin blockchain...
No doors have been shut. Bitcoin is moving more than 2 billion dollars per hour, worldwide. Making up new numbers for block generation target time out of thin air is silly. Adding gizmos and widgets to try to patch up a broken block generation target time is even sillier. As I said earlier, feel free to start an altcoin. Cryptocurrencies are one of the few truly free markets in the world. But these proposals are incompatible with Bitcoin.