I have not legendaries but i think about make some after few years in this game already. And i have next idea, i think it would be very usefull, jsut think about it: instead of swaping runes better way would be if you can feed runes (sigils infusions etc) to your armor so it has that rune available like changing stat, so much quality of life. For such legendary armor i would spend some gold!
For example, you can freely swap stats of newly crafted legendary armor, but when you fed it scholar rune you have another tab with available rune stats (scholar). So you need 6 scholar runes into 6 lege armor pieces and then you dont need space in inventory and more comfy cahnging stats. Then you can feed another runes but make cap of runes like it can eat maximum of 15-20 diffrent runes, that would be perfect dont you think? same with infusions and sigils on legendary weapons, Truly legendary gear by looks of it and by usefullness!
p.s. englando is hard i know ecksdee