The problem with Valve's TF2 updating scheme right now is that change to gameplay isn't coming fast enough. In Dota 2 or heck, even CS:GO, balance changes happen casually in updates. Just a while back they changed the inaccuracy for the AK/M4 to encourage tapping and short sprays.
But in TF2, we get droughts of weapon balance because they're sticking to this slow and painful scheme of releasing balance changes only with major updates, which happen months and months apart. And if those balance changes suck, we're stuck with them for another 6 months and we have to wait for them to see if they fuck up the next balance update.