With old expansions mostly being only used in the Wild is there any point in keeping cards if we can just DE and continue in Standard mode? Also is there a way to track what cards to DE moving forward with what is in our collection ? :)
Easy example about why dusting wild legendaries isn't worth it unless you're absolutely sure you'll never touch the wild format.
1st rotation (2016): You dust all your 64 rotated legendaries and use the dust to craft 16 standard legendaries. 2nd rotation (2017): You dust your the previous 16 legendaries and craft 4 standard legendaries. 3rd rotation (2018): You dust your previous 4 legendaries and craft 1 standard legendary.
There you go, 64 legendaries turned into 1 after 3 years.