The feature I used the most on that website was just viewing a bunch of champion models/skins for entertainment or get art references when doing fanart.
Yes the official splash arts have more details to each champion but the splash art doesn't give the viewer a good view of their anatomy completely and how they can move, even the isometric camera in game obviously isn't useful.
There were times where I would get certain proportions of the body just slightly wrong because of the lack of a good reference.
If this addition of making a model viewer for the client or make it as its own app for computers/touch pad machines is too much then perhaps your artists or maybe some of your famous fan content creators can be commissioned to draw official references aslong as the artstyle is consistent and we get a good view of the champion uniforms or markings on their body, outfits, accessories and make sure to cover all 4 sides and make shape mannequins as a starting point of how to draw each champion.
Thanks you for reading.