The numbers are too large so that even if you were to go through it randomly or even sequentially you won't find a wallet with coins in it.
If you want an example see this:
http://directory.io . That is a list of every bitcoin private key that can possibly exist ever. Try finding one with coins in it.
PS: To the nit pickers, yes, bitcoin private keys are 256bits and electrum seeds are "only" 128 bits. The concept is the same though - too large a hay stack.
One point - though. You seem to talk about Bitcoin Addresses and Private Keys. You have to work and insist on a Bitcoin address to find the Private Key of it. And it would be worthless. (like a password attack on a username?)
However, on Electrum, there is no username/password or PublicAddress/PrivateKey combination. Simply a text with some dictionary words (not random alphanumeric) and that can lead you to any wallet randomly. You do not need to insist on cracking a specific wallet and spend time on a one single wallet.
I guess as no longer anyone answers my original post, then I will not dig this issue further, that would put Electrum author in a bad position. This kind of monologue I am insisting on would be really baseless, as I do not understand encryption etc. I would not create some fog on an issue I really have no clue and even understand.
I just wanted to make an informed move to avoid some jeopardy (due to lack of knowledge). As not too much replies came, there seems to be no risk and if there was any, Bitcoin community would have realized that much more before than me.
. Now I feel it would be OK to create Electrum wallets, put Bitcoins in it, then forget about it for some time.
In any case, if Electrum author sees this message, and clarifies that, that would add an extra comfort.