1 block up to 20MB in size every 10 minutes on average is cool but it could be a dissaster if couple of such blocks are generated just few seconds appart by the same miner or miners that agreed on longest chain. It also does nothing in terms of speeding up the process of transaction confirmations, waiting over an hour for 1st confirm would still occur so how about 5 blocks up to 4MB in size every 2 minutes on average? Makes perfect sense to me but feel free to debate, I might be missing something with this whole deal.
Having blocks come quicker provides no advantage over 10min blocks. Why?
The same hashing power; faster blocks means more orphans and if we had 1 block every minute, we would have 10x less security from a double spending attack. Right now a doublespend would take ~ 2 hours, if 50% hashpower was used. (actually i'm probably wrong, its longer)
Now if we reduce blocks to 1 minute blocks it will take far less power to doublespend and a quicker time.
Basically, faster blocks will be less secure, cause more orphans and pretty much just bloat the blockchain. So yes, you are missing something.
An attacker with 51% or more hashpower will own the network regardless of block time. If we drop block time to 1 minute that same attacker would still need 51% or more hashpower to successfuly double spend. The only way to "protect" from double spends is to wait certain period of
time, not number of new blocks added to blockchain. If I wait 1 day and only then send you whatever you bought from me it is almost impossible you'll double spend on me, block times can be 1 second or 1+ hour.
The same goes for orphans, it makes no difference how many of them will be created if you wait long enough. I think you are underestimating the traffic volume and existing bottlenecks when it comes to moving 20MB blocks around especially if they are spread just seconds appart (not orphans but blocks that add on top of each other). Few such blocks would basically stall any nodes except very fast ones and that does not really work toward more decentralization because over time there would be less people running full nodes.