Obviously there is an obsessive, CULT-like following to Ledger's Joker, an absolutely timeless and rabid fanbase. So, for that, I get why they'd open with this. Those folks are always gonna buy again and again, so they're basically guaranteeing a given amount of sales.
If you ask me though, a huge aspect of this pick is that they can just immediately look at what doesn't work on the HT and IA figures, and just...not do those things. Or rather, make different, blatant, minute mistakes that people will tear apart. But they've got two points of strong reference to build on and adjust for, and that works in their favor.