Well Jack1, just do it, and regret it. Just think about the fact archers that are already wearing light stuff and having 9 athl will still kite with 11kilos of arrows on their back.
Also, if it has to happen, I simply hope you know you're going to screw every 2h archer + archers that use a 1 slot 1h (2 slots from bow + 2 other slots for ammo leaves no free slot) + archers that loomed a short sword (if you want it back to 1 slot, or to nerf the shit out of it to make it completely uneffective), and it will end up, as you said, archers taking weapons to block, and will keep running even more.
Thing is, I almost see no one on EU1 with a rus bow, and really, I see 1 archer on 50 with a long bow. They simply stick to the low PD bows, which give advantages when PD bonus is maxed out (i.e : nomad bow and 6 PD, with either bodkins or tatars). And it's all those guys that use low tier bows that got most potential when it comes to run.