The design isn't that conservative, it's just that it's similar to the 7 and 3, which have all adopted the flame surfacing design philosophy of Bangle quite well, lots of convex/concave to show light and shadow.
If you put F10 and E60 side by side, E60's surfaces are relatively flat. To me, what E60 shows is softer flowing lines (which at angles from rear quarter view seems a bit fat), while F10 has more tout shapes to show tension and athleticism.
If F10 came out after E39, it would be rejected also.
2008 528i: Ti Silver/Black/Light Poplar Wood, ZPP, ZCW, STEP, Comfort Seat, Heated Rear Seat, PDC, Xenon, Nav, iPod. 35% ceramic tint. VentureShield Clear Bra.