Why did Obito massacre the Uchihas?

Now we all know that it was Obito who helped Itachi massacre the Uchihas. But what could be his reason?

1. So he could recruit Itachi?
I don't think this would make sense because the Uchihas are starting to rebel against Konoha. And with a little persuasion and a little acting the he's Madara, he could recruit all of them. And the whole Uchiha clan is definitely stronger than a single Itachi.

2. To steal their sharingan?
Doesn't make sense also. As I have said in number 1, it's probably easy to recruit those Uchihas at that time and sharingan eyes in an Uchiha body with an Uchiha mind that is rebellious against Konoha is much much better than eyes alone.

3. To prove that he is Madara and he wanted revenge on the Uchihas?
Nah. It wasn't revealed that Madara is "alive" until the Itachi and Sasuke fight.

4. To convince Itachi that he is Madara?
Why would he need to do that?

5. To force Sasuke's strength growth?
Doesn't make sense.

So what do you think was his reason for this action?

Umm, probably to make sure that no one else could take control over the 10 tails and stop them?

I always saw it as a combination of what IMUSTbeThedevil said and his admiration to the real Madara who likely wanted them dead.

I also assume Obito killed off... the uzumaki clan. Hence the whole special charka and abilities likely made to suppress or seal the tailed beasts. An other force likely able to stand up to him or take control of the tailed beasts. But this has not been confirmed or even strongly hinted at. But I think there is some proof out there. Did obito not rule as the Kage of the hidden mist or control the kage of the hidden mist at one time. And did I not read that the uzumaki were killed by an attack from the mist? I could have half of that wrong.