It seems that teams don't trust their drivers who get paid millions of $$$ to not crash into each other; says a lot about the teams confidence in their drivers doesn't it?
I think it is very easy for two drivers to crash into each other.
A wrong assumption is enough (eg. "Webber is going to yield, I can move right") for the whole thing to end in a disaster.
And having Red Bull issued that warning that team-mates fighting each other can be very dangerous points-wise, I think it's normal Ferrari decided to do it the "hard way".
Team-mates battling is always a very risky thing, as we have seen in the past. Also because the rivalship within the team is unique.
Also, they don't necessarily need to "crash into each other", they just need to break a front wing; which is nowadays very easy to do.