Anyway to move past this conversation, again, pick 5 dlc characters of franchises who don't have playable characters but not a main protagonist
Easy
Marisa (Touhou) - This one's a bit iffy, since she's the deuteragonist and (after the first 2 games) Marisa and Reimu are always playable, but Reimu is distinctly a cut above. I'd much prefer Marisa, since she's my favorite character, and she could bring a fun mix of magic and broom action, plus the ordinary magician aesthetic has yet to be taken. If you don't think Marisa is eligible uhh... Utsuho I guess? Her theme is a banger, and Smash could always use a Nuclear Hell-Raven
KOS-MOS (Xenosaga) - Yes this one also counts, Shion is definitely the protagonist. KOS-MOS has both ranged and close up attacks. Maybe a T-elos echo too?
Edea Lee (Bravely Default) - While all the characters get focus in the first BD, the order of attention is Tiz > Agnes > Edea > Ringabell. I
need that sweet Bravely ost, and I think a Brave/Default system could be interesting in smash. Plus, I say there's no such thing as too many swordfighters.
Gemini Sunrise (Sakura Wars) - Ok, this isn't from that faked leak from a while back, I've wanted Gemini since Project X Zone. She'd just be soo cool. C'mon, who can say no to a Samurai Cowgirl?
Alisa Amiella (God Eater) - Monster Hunter but anime and with an actual character. A bruiser with range, she can join the Ike/Hero club.
Just noticed all my picks are women. Huh, that's an interesting coincidence. Also, most have a sword + gun combo. Also a coincidence. And, I like the music from all the series. Another coincidence. And now I've just realized they all have outside chances...
Personally, I think Smash needs to pull a little bit from every era. New and old alike.
Maybe this is parsing it too much but how old is old? Is a character from before 2000 old? What about 2005? Likewise, how new is new? Wii era? Wii U era? And can characters be too new? Personally, I think same year of debut is too new for smash, maybe a mii costume; yes Roy and Corrin, but I'd rather that be the exception than the rule, and I think Sakurai and Nintendo should be more critical of 3rd parties than 1st party characters.
On the whole though, I agree with you, there should be a reasonable mix. imo the balance should be heavier towards legacy/old characters, maybe 3:2, but newer characters should have an opportunity to join the fight.