I agree.
Changing stats on Legendary items usually requires rune or sigil change on them. Which means any character running at least two builds and having at least one legendary spends more and more gold to change runes. This could me solved with some sort of “rune system rework”, which definitely is not an easy task.
Instead, we could solve problem with very little development expenses by introducing infinite upgrade extractor. Of course, due to immense power of this item we need it to be rare. One of examples would be making it same as “infinite hairstyle kit” – droppable from Black Lion chests and sellable on TP. I imagine with same drop rate it would be definitely not cheap and basically cost as another legendary item, thus only those who have several legendary items could pursue obtaining it, and as a result it will be a major upgrade to their legendary setup.
Currently the problem is not that severe, we only have legendary weapons and backpack. But with legendary armor it definitely would be. Personally i feel no will to obtain legendary armor because my two main “builds” require rune change, which will cost gold and defy all advantages of selectable stats on armor. It is more practical to have two sets of ascended armor in that case