Either Kotobukiya were cautious about creating another classic Thanos considering Bowen has 3 in the market that 1/6 collectors adore and thought maybe there wouldn't be any takers for this one and tried something new. Maybe it was Marvel trying to push their Marvel Now Costumes to see if there's a market for it
Or maybe there's just no planning in the way they do their releases. They had the opportunity to reopen the classic avengers line with Black Panther and now add Vision to it and wasted that opportunity. No way to really tell but it's definitely a lack of focus on the Fine Art Line. That parts a given
