Who gives a shit what people think of Fire Emblem and its fandom. People shouldn't complain because the roster is being improved upon further, which nobody was honestly expecting to happen before Mewtwo was revealed. People who complain about the character choices seem like the type of people who throw their toys out of the pram if they don't get exactly what they want. The decision to include FE Roy is ultimately down to the people who are in charge of such decisions. You can't make everyone happy; but Roy's inclusion will undoubtedly satisfy a majority of Smashers.
Smash is pretty huge. I would think it was a minority complaining about "shitty" clones, and the inclusion of Roy will satisfy a large number of Smashers because 1) it's a Melee veteran, and/or 2) it's a new playable character. Everyone loves more choices, regardless of how different or similar they may be to what is already available. Well, everyone except those type of people I described in my reply to Nova above.
My extra opinion: Since Roy will undoubtedly be DLC that you will have to pay for, he will not be so similar to Marth and Lucina. I trust Sakurai's integrity to not charge for clone characters.