For most of the MMOs I've played I feel like the combo thing is a little out of the box so it'll be a learning curve for most.
One thing I think is pretty cool about them is that, in my opinion, they will promote a more tight knit group/better of understanding of the other classes you are playing with. The reason I think it will promote a more tight knit group is because sure any random pugs can use them, but I think it's somewhat obvious that a team that knows how each member plays will have an opportunity to be really effective with these combos.
One thing I am definitely excited to play with a little more in BWE#3