Tableau already allows images with transparent backgrounds in dashboards. See How to use transparency for images in 8.1? for tips on doing that.
As for "3D, rounded edges, etc.," these things violate all the principles of good information graphic design philosophy of experts like Stephen Few, Edward Tufte, etc. Presentations that include that "chart junk" only distort an obfuscate the data. I would vote against any move in that direction.
Thanks for the link, ill read through that,
as to the extras, maybe i over cheesed it, but im thinking info-graphic style art, something that allows the level of design to stay fresh in current trends. Tableaus colours and shapes are a bit to boring ol` microsoft for me and look dated from the outset. Maybe this is because i cant work out a way of using the very convoluted formating tools or maybe its just not there. i dont know.
i am thinking.. this: Information Is Beautiful