reducing the difficulty. just makes it cheaper for miners to find blocks. this just results in more miners jumping in.. which ends up increasing the difficulty again.
Reducing the difficulty in a way the average block time decreases to less than 10 minutes.
Assume that we decrease the average block time to 2 minutus. The difficulty will increase with the increase in the total hashrate, but the average block time will still remain 2 minutes.This will lead to a less congested network and lower transaction fees.
Again, I'm not saying this is a good solution. It would make the network insecure. We don't need it all.
reducing the average blocktime also requires messing with the reward (at byte level) which changes when and how many times the block halvings happen and many other nasty messy implications that then also need to be fixed as a consequence..
but even if done, and all consequential bugs fixed. again it lust produces a temporary result. because mining pools will just again increase asic hashpower if they can start making more money because of cheaper hashpower.