Basically you want Chrom to be similar to Ike (to not waste much development time) and/or replace him? Your opinion is fine but we don't know if Chrom is in or how he plays. It's like assuming Ganondorf with a sword will just be another Ike (could be true, actually).
I never said that.
Chrom is a character who, like Marth and Ike, does not have much in the way of special powers or abilities. Aside from being athletically impressive, he holds the neo Falchion and all its powers that are within. Aside from his command over the Shepherds, that's basically it. This means that, to make a moveset for Chrom, you need to surmise an immense amount of creativity that only intensifies with each and every character that is added. Every character they add is given a specific style of gameplay, function, strengths and weaknesses, and of course an attempt of having original moves.
Which is perfectly fine. We did it for Captain Falcon, Zero Suit Samus, and to a lesser extent Sheik, among others.
But creativity poured into creating Chrom as a wholly original fighter, keeping the current roster + Ike in mind, is essentially making a moveset at least five other characters could handle comfortably. This is doable, but that doesn't mean it's a good idea. We can just as well utilize this creativity to better yet represent something completely new and fresh, like Shulk, or revise a character like Ganondorf, among many other possibilities.
To add Chrom, one who is relatively (as in, a humanoid swordsman compared to the rest of Nintendo), means they are just adding another Fire Emblem character to appeal to fans for the sake of adding another Fire Emblem character to appeal to fans. Which is 100% totally reasonable, as Smash Bros is the epitome of fan-service. However, if we're going to do that, why not add someone new, fresh, and interesting like Anna or Robin, keep Ike, and repurpose the moveset for someone else? You still get fan appeal, and you can represent more of Nintendo as a whole.
Do you not want to see Marth, Ike and Chrom because they're blue-haired swordsmen or because of similar gameplay? I see "diversity" thrown a lot but I'm not sure what they mean. Some want gameplay differences and others want females and villains.
Diversity, characters with the most contrast to existing characters. Appearance, art style, gender, gameplay potential from source material, generation, any tools/weapons they may have, all contribute to diversity. And yes, I think it's very important. As do many other fans, as well as the director.
Maybe Marth, Chrom and Robin would be your picks.
I wouldn't be so bold to make an assumption that is my pick, but I would be okay with that. As I would be okay with just Marth and Ike, just Marth and Chrom (most likely outcome), Marth, Ike, and Robin, Marth, Ike, and Anna, etc. Anything but a combination of Ike and Chrom or Ike and Lucina. Even ALM would be better than that.
Being the reincarnation of the hero's spirit is not a surprise that they have an identical fighting style and Toon Link is not supposed to represent the classic hero but one of the timelines that the Zelda timeline was divided into after Ocarina of Time. And even characters with a similar moveset can play differently and bring their own set of flavors to the table. Several fighting games have shown that in the past but when Smash does it, it becomes a mortal sin.
I never said it was silly for Toon Link to have those items. I said it was silly for Toon Link to have those items, when you could get far more value from development time by having someone who offers a greater contrast in gameplay potential, and thus offer appealing options for a greater range of players, have a greater range of gameplay experiences, and thus greater value from the product. It's not like making Link as slow as he was in SSBM and SSBB was even an intelligent design direction, given that he's had consistently poor performance three games in a row. If he were just a smidge faster (more practical for any game remotely similar to a fighting game), we would never have needed two Links with largely statistical differences.
Yeah, several fighting games have had similar characters, and that doesn't mean it's okay. FGC is still sore about the recently revealed Decapre in USF4, and they are still sore over Evil Ryu. Don't think anyone has ever argued that the sheer amount of shotos that Street Fighter has ended up with is silly. Sure, people play the characters, and they will offer different gameplay experiences, but the fact of the matter is the fans can more than easily chime in for ideas for things they would actually want to play as, or options that they do not have. An original character, just like any other, will still garner appeal as long as it's good, fun, and balanced, so it's not like the argument that people will play it holds any water, either.