Why not somebody invent a wallet that can keep all the coin
Do you realize how many alternative coins are there ?
And some lived only for short time - not worth the update work in my opinion
Exactly.
If you are asking for a wallet for every alt-coins?
It is just meaningless as new alt-coin shows up and dies down everyday.
You may take a look at
https://bitcointalk.org/index.php?board=67.0If you are asking for a wallet for bitcoin together with a few major alt-coins?
It is unlikely to happen as the maintenance will be just too hard.