There's a bunch of things to consider here on whether or not skins are made: How often people play X champ, you're right time is a factor, difficulty of making a skin for X champ (Jinx, Zac especially), general themes and how fitting they are for X champ, how amazing is the fan idea, and does this champ need a complete overhaul.
Talon fits a couple of those criteria, but how many skins does Guy Who Stabs Things need to get the point across that he stabs things. Dunkmaster Darius came out because he quickly became the king of it, and somebody a long time ago came up with a great concept. Furthermore, it takes a long time to take the rough drawn concept, and turn that into new champ model, then properly code it in right. You wouldn't want to see Battle Bunny Riven on say the Rammus model. That just leads to broken hilarity.
Also, Battle Bunny Talon? On a guy that doesn't hop around at all? It makes sense for Riven because she's always jumping/dashing. But not for someone who's most complex animation is a spin.