You have already mentioned one good thing about
e6, it blocks the c4-bishop. It may not seem very important, but the white's attack on
a2-g8 diagonal can be rather unpleasant later on, especially after white's moves
Other important factor is the
Nd5 can be sometimes very unpleasant, so you want to avoid it. It potentially stops even
Bd5 (for example after b5).
Black in these structure usually opts for a central break with
e6 supports this plan. That's another reason for playing this move.
We shouldn't also forget the fact that
e6 allows to develop the bishop on
To the "weak" pawn on
Here's the deal. You protected
f5, you have avoided some nasty moves like
Nf5, you have made some space for your bishop on
f8... but there's a price for that. Your d-pawn has become a bit weak.
It's not such a problem, though. Bishop and queen is guarding that pawn and later you can even put a rook on the d-file. Also, as I said,
d5 should be coming. That means the weak pawn won't be there forever.
I would say
e6 has many more advantages than disadvantages... so I would go for it.