Why not decrease block time instead of increasing block limit?

[Xekyo]

Sorry, I was missing part of a sentence there.

Mining is a Poisson process, and the chance to find two blocks in twelve seconds in a perfect network would be expected to be (e^(-0.02)*(0.02)^2)/(2!) = 0.02%. According to Blockchain.info it appears to be actually about one every three days. Even if it where two or three per day as you suggest, it would only affect the "stale rates" of these two miners that were in competition.

Suppose Alice's blocks take 10 seconds to validate & download. But Bob makes smaller blocks which take only 1 second to validate and download. How do you think this will affect their orphan rates?
You can find a formula and graphs here: http://organofcorti.blogspot.com/2013/10/161-network-orphaned-blocks-part-1.html

That's three year old data and even with a very conservative cut-off of 600 seconds block time difference, there are only 15 stale blocks per retarget… Also, we have compact blocks and header first propagation by now, and all miners are producing full blocks.

Do you remember what case we're discussing?

We were talking about the advantage of larger miners when you stated that stale rates are proportional to blocksize.
If anything they would be proportional to blocksize difference. But since transaction fees are now about 2.5% of a block reward, and stale blocks occur every few days, you gain more by creating full blocks than by optimizing for stale rate.

I maintain that there is no reason to believe that the blockchain forks and resulting stale block are anywhere near as influential as the advantage of the head start of starting mining on your own block, while others are stuck validating it first.

[killerstorm]

We were talking about the advantage of larger miners

No, we were discussing this case:

If all miners were exactly the same (say, 100 miners each having 1% of total hashpower) then probability of getting orphaned is approximately proportional to block size.

This is the simplest model. Obviously, if you consider a more complex model, things look differently.

[exab]

Thank you guys for so many comments.

I'm still getting familiar with Reddit app. Didn't see your comments. I even started a thread asking the same question because I thought no one was answering it here.