b, c, and d moves being air unblockable without barrier doesn't really change much, i think.. most attacks just don't have enough vertical reach to catch someone jumping away, especially on IB, and if you fight someone who actually knows when to jump/ib jump out, then i can't really see how it would be very useful, when you also consider lowest air barrier. like zeth said, there is nothing stopping someone from doing lowest air barrier right after a jump to be safe from air unblockables. increasing jump start up on neutral (not direction) jump, introducing throw reject miss state for air barrier, or just nerfing barrier/barrier gauge in general would be a better way to deal with the abundance of chicken blocking in BBCS (america, at least)
but this is all theory fighting anyway, who knows how the game will change once we actually play it (if we do)