Anyway, I'm just trying to bring new solutions to the difficult blocksize issue. If this is a bad idea, that's OK with me.
even if you put code in to hard limit a block to be atleast 7 minutes, (or any number you think of, but lets use 7 minutes)
then when the mining farms that can make blocks in 4 minutes will then waste 3 minutes doing nothing.. and then at 6:59 its then a fastest finger first..
this will lead to many blocks being made far before the time as things ramp up and still become a lottery
this would mean that the difficulty does not change as its accounting for the 7th minute.. even when miners are queing up solved blocks even after a couple minutes.. meaning that after a while miners could solve 2,3,4,5, etc blocks before the 7th minute. which means they can manipulate the chain to their advantage and cause issues around security.
instead of a time limit hard coded.. which will affect difficulty, a much easier option would be to change the code from 25btc for an average 10 mins.. to be 6.25btc for ever 2minutes 30 seconds.. that way its still based on solving a complex puzzle that wont lead to difficulty/security issues, and the 21mill limit will still be enforced.
though i do not propose my own suggestion.. its atleast less risky to bitcoin than your time limit code