Why does everybody keep focusing on the blocksize issue, when the real issue is block generation frequenc?,. Is it just that blocksize is an apparently trivial change that everybody can understand, but they don't appreciate the broader implications such as possible mining centralisation.
Frequency raises the issue of time-warp attacks/network propagation delays. This problem has been solved in GoldCoin (GLD), which can handle 10X Bitcoin's current transaction volume.
See most chains accept blocks that are hours into the future or in the past.. GLD only accepts blocks that are at most 45 seconds into the future and 2 min 45 sec into the past. This makes it very difficult to do a time warp attack on our chain.
It is not a simple change for bitcoin as it would invalidate some miner blocks most likely, and that may cause controversy.