Right now people like to hype up stat swapping with legendary weapons, but the truth is you are better off making ascended weapons unless you want that fancy skin. You can make a whole array of ascended weapons to fit your different builds and get a specific sigil for each one. Trying to do this with a legendary means you either have to overwrite expensive sigils for some builds or make an ascended weapon to use your skin on so you can keep your nice skin and get the benefits of stat swapping with proper sigils. For players who want to maximize their many builds potential, legendaries fall flat as a means.
Sigil swapping is the best way to make legendary weapons into the best most adaptable weapons, and even make some duplicate legendary weapons useful. Although it will completely trivialize duplicate two hand legendary weapons and make them worthless (not that theh aren’t nearly worthless now). Right now though there is little reason to go legendary over ascended if you want the maximum potential of several builds that have different sigils.
Sigils might not seem so bad, but if you go between builds a lot or use more expensive sigils the cost would start to add up quickly. In the long run those ascended weapons are cheaper if you plan to swap builds a lot even if you already have a legendary.