Why is this a problem for you when a5 merc is NEVER played? A5 merc is still useless in 2.4 because of a2 merc aura utility. And still insight makes way more sense on a sword than on a bow. And your issue with only early game futility of a2 merc is a small one especially when most people spend their time end game. This issue would only be for single players that don’t play online, which would be a terrible business decision to not have insight on a sword when most players play online (and again from a fantasy standpoint it makes way more sense for the meditation aura to come from a sword, not a freakin’ bow that almost no one would use on a merc for best in slot builds).
A main point for insight on a sword is so the a5 merc can use it with a lawbringer offhand. Then the warcry/singer barb can replace the light sorc for bis key farming (makes the most sense because warcry is getting buffed in 2.4 so why would they not add this very important change idk). Also insight on a sword can easily open new cool merc builds for ww barbs and other physical or caster builds too. You know what insight does on a bow for MOST people? Nothing lol.
Physical bowazons are a meh dmg spec that’s super expensive and can’t optimize teleport speed compared to really fast tele specs so barely anyone plays it except for rich people for the sake of maximum optimization. Ele bowazon dmg may be a lot lower compared to physical, so might as well play a sorc/druid/pally if you want an element-themed build that can teleport WAY faster. And buying quivers constantly is a nuisance. If the devs buff them drastically then it’s a maybe but for now it’s a definite pass for most people.
Lastly, insight as a main bow for a bowazon of any spec is just inferior to many other weps/runewords. It’s best for mercs not players.