They really are not difficult to counter. Does every boss in the game need the same slam mechanic? No. However, once you get the counter for it down you know you don't need to change tactics when encountering a different boss. It actually makes it rather simple to deal with. I get pushed back a little on occasion, but almost the only time I get launched hard is when I do it on purpose. If you want to have a tiny bit of fun, run up to a boss on a Warlock and double jump just as he slams. If your timing is good you don't need your ship to get to another planet. :)