I asked the exact same question a few months ago in some "Best looking keyboard" tread here at this forum. I am pretty convinced that the Roland staff was very inspired by the ARP Quadra futuristic look. The same sleek design, they are both very colourful and we see the same orange block lettering on the panel layout. Apart from the colouring coding of the program buttons, I will say that Rolands design for JP-8 was a departure from its predecessor (JP-4).
Roland Juno-60, SH-2, SH-101, Juno 106, S-330, MKS-20, JV-2080, Moog Prodigy, Solina String Ensemble, Yamaha DX-7, EX-5, P-250, Cheetah MS-6, Novation Superbasstation, AKAI S-3000CD, Korg CX-3, Alesis ION.