I'm glad they did, because honestly I don't think Jared Leto is really all that marketable, and if they thought they could keep Jeff Bridges under wraps while promoting the movie in favour of Leto, well, chances are there wouldn't be nearly as much curiosity in it by now, and chances are the movie wouldn't attract nearly the same amount of attention. When it comes to Tron, Jeff Bridges is at its core, so it makes sense for him to be part of the marketing. There's also a chance for Jeff Bridges to deflect some of the bad will generated by the presence of Leto during their marketing.
I’m really excited for it!