The thing is that this wouldn't really solve that much.
I mean the slow pace of the lore releases isn't because riot has problems with filling the gap thats left behind by the IoW,its because they simply became much slower,which is partly because they put more thought into the lore(in the early days making the background of a champ a "mystery" without much thought about it was ok) and reboot certain individual champs.
Bringing back the IoW won't speed up the lore releases and will in fact probably slow it down even more(because then they'd have to rethink some stuff they prepared for).
They would also have to create viable reasons for certain champs to join the league.I mean can you explain to me how
could join the league of legends,without getting captured or summoned against her will?(Because those would pretty much ruin future stories for her,if she's captured,she can't interact with anyone and if she gets summoned against her will,that means the league can do it with anyone which is extremely op)
Not to mention that retcons are probably gonna happen even if they keep IoW(the freljord event retconned a lot even though the league was still a thing at that time)