Well, of course. You make a good point, but I think most of the assumptions made here are considering what current, regular gamers want or would think. Casual gamers and retro gamers (ones that stopped after the 16-bit era and only return for the occasional party/social game, like Smash, nowadays. Many, many college students are like this nowadays,) would mostly consider Tails just another classic icon of gaming, on the level of Megaman, Samus, or anyone else from long-long-ago.
I'd suggest a poll to see how many people are largely indifferent about two Sonic characters instead of Sonic and Megaman/Bomberman/etc, but I think we'd have to agree the Smash boards tend to be pretty biased toward a 'hardcore gamer' view, which, as far as Nintendo concerned, is really only one piece of the marketing pie.