I think it's kind of like losing the bike's identity. I know if I see twin round lights coming towards me that it's quite probably either a speed or street triple. I think unless sales of the Speed Triple bomb with the new lights (and I certainly don't want Triumph to fail) then I think they're a certainty for the next Street Triple.
As others have said, the look of the bike was definitely a factor when I bought my Street (less than 6 months ago) and the lights are an important part of that. Give people options by all means but I think Triumph are making changes for the sake of change and are underestimating what people think of the current bike. Are they reading the press and believing it? I did read a road test earlier this year of the Street Triple that described the round chrome lights as dated - horse-s**t I thought and bought one anyway
Wonder how easy it would be to remove the slanty eyes and replace them with some round ones?