Agreed. I remember when Melee came out and Marth and Roy were in it, I had no clue who they were. I always expected they were characters from a more Japanese series at the time but wasn't really familiar with Fire Emblem back then. Sure they weren't even close to the popularity of Mario, Kirby, Link, etc. but that didn't stop those characters from being a lot of fun to play as well as adding some good variety to the roster.
I am all for characters just like that in Sony All Stars as long as they are well planned, well designed, and fun to play. The main thing I do not want to happen at all in Sony All Stars, which started in Melee and followed over to Brawl, is the fucking clone characters like Link and Toon link or Fox, Falco, and Wolf. All are really cool characters but when they are basically the same down to the Final Smash, what is the point. If they wanted to do pure fan service with other characters from a series, then just make palette swaps (say Fox palette swap is Falco and Wolf). This way you aren't padding your roster and you still have the fans pleased. The other problem by making characters so similar in that sense is that when it is apparent one of them has the edge over the other, the others are worthless, what is the appeal to play the inferior character of the same play style besides appearance?
So I do not want some bullshit with Sony All Stars by having, let's say, Radec right now and then Rico comes into the roster with a damn near identical play style. I would prefer to have as many different game series represented in this game and if they feel the need to add Rico or another character from Killzone, they damn well better be 100% unique.
As been said many times as well, like you said, when you look at what Sony is pretty much going to have in this game just from their own characters
Kratos
Fat Princess
Radec
Sweet Tooth
Sly Cooper
Parappa
Cole
Nathan Drake
Sackboy
Ratchet & Clank
Jak & Daxter
Sir Daniel Fortesque (Damn well better!)
You have a damn solid and incredibly varied character roster at your disposal. Every one on that list (unless they make Clank and Daxter their own characters) is also from their own individual games spanning over 15 years of Playstation goodness. Add in Crash Bandicoot and Spyro and others from the 3rd party possibilities (I classify Crash and Spyro as 1st party, seriously stupid they don't have the rights to them anymore) and dig in farther to the lesser known characters like Blasto and there is just no reason to complain about the roster lineup.