I admittedly have not played much Vintage lately, but when I was playing I tried out Transmute Artifact several times and I was never really happy with it. Tinker has a big edge on Transmute Artifact because it lets you cheat out expensive artifacts. It's like stapling Demonic Tutor to a Show and Tell.
Transmute, by contrast, always functioned like a worse version of Trinket Mage, in my experience. Sure, you can tutor for a cheap artifact at sorcery speed, but... how often is this the best card for that job? Assuming you really want to get something that costs 2 or 3 instead of 1, now we're talking about paying 3UU or whatever to tutor... and we're crossing into what Tezzert costs. On top of all that, Demonic Tutor does the same thing for X+1B instead of X+UU+sac so...
I think it's just a function of a card that is really legitimately broken just not being competitive with other broken cards.
Now, if there was a deck that really needed to pump artifacts into the graveyard or really wanted another useful sacrifice outlet, maybe we'd be talking. Transmute does put two artifacts into the yard, and if that angle is something you can exploit, maybe it has a place.