.. does not put items into it.

It's really bug?
By-design extraction pipes and auto-push (like quarry) machines only can put items into pipes.

no bug here, hoppers always point to the block you click on, no matter if it can accept the items or not

Pipes do not have an inventory that can be accessed by the Hopper. Not even the BuildCraft Chute can do what you are trying to do.

It is also possible to point the vanilla hopper into a block of cobble. The orientation of the Hopper is based on how you place it, and not what it can logically connect to. If you want it fixed ask Mojang :)

Also it would be a useless thing to let a hopper send items into a pipe. Because then it would act like a pipe that can only send down. It would only make sense when the Cute (Hopper) Is like a TinyHopper (Rotateable and Redstone controll). XD

I know about pointing. But i think it should output items into the pipe, it's not a bug, it'll be a feature.

BuildCraft pipes are simple for performance reasons. Giving them an accessible inventory will have a negative effect on performance.