Alright. First of all, stop whining.
Secondly, there IS an online indicator.
No, it doesn't show the TIME or the DATE or any of that stuff.
Bob: Does it show the location?

No Bob, it doesn't show the location of the player.
Carl: Does it glow?

And no Carl, it doesn't glow.
[Names are non-fictitious. Any resemblance is perfectly intended].
Here's the simple trick (and it doesn't always work, but its better than nothing).
Visit the player's base. Look at the amount of resources they have in their mines.
Divide that amount by the number of resources that mine generates per hour.
Voilą... that was how many hours ago that player was online.
Where does this go wrong?
1) The player was attacked recently. Then, try to look for a collector or mine that hasn't been destroyed. Else, just make a guess based on how many resources the mine has.
2) The player JUST got online. Servers take time to show the rebuilt or collected version of the player's village.
3) The player is lazy and doesn't collect resources unless he gets free chips.
4) The player has full storages (heck, why would you kick someone who has those?)
Basically, it is possible to make an approximation about how active the player is or when he was last online. Why do you need a stupid indicator?
Jim: Me stupid. Me no understand.
Example?
The Culprit visits RandomIdiot's base.
RandomIdiot was attacked and half his village is rubble.
The Culprit looks for a mine that didn't have an health indicator (which means it wasn't attacked).
He clicks on it and views its info.
This mine produced 3000 gold over hour and currently has 90,000 gold produced.
That means RandomIdiot was last online 90000/3000 = 30 hours ago.
The Culprit kicks RandomIdiot out of the clan.
Easy?
If you knew this trick and still wanted an online indicator, please type "Facepalm" in Google and look up the images that pop up. Yes. That's my reaction.