The issue most folks have with desynthing is that the risk of blowing stuff up almost makes it not worth attempting if you have to buy the ingredients. Having just finished the **** levels of goldsmithing to 58.... I lost about a million gil just because I blew up so many of my finished products. Whatever stuff might desynth to would have to be quite pricey to even bother.
I think the Vir subligar was a case of "this is a ridiculously expensive and suspiciously useless item" and maybe even SE hinted they were adding another means of getting Cashmere cloth so crafters knew, because at the time it only dropped from Vrtra. (They later added it to Bahamut V2 as well, which is where I got my Sha'ir manteel from.) I think it was also eight million gil for the subligar back then.
Edited, Nov 16th 2012 11:55am by catwho