Roshi blew up the moon when his power level was around 180 according to Raditz's scouter in Dragon Ball Z and Goku had a power level of 420 when he fought Raditz.
Technically, we never saw Roshi's power level for his actual "fighting form", when he gets slightly more buff, like how he looked when he faced Tenshinhan. And the form that he used when he blew up the moon was even bigger. Back then, the Kamehameha also was almost a 2x multiplier.
Tien has no real personality besides being serious.
He also had honor as a pretty big part of his inherent personality, even though it went against everything he learned from his master, which eventually leads to their conflict when they attempt to cheat during the finals against Goku. Of course, due to parting ways with his master, he immediately drops his former arrogance and tries to befriend Roshi's disciples, which I guess makes him too much of a "good guy" too quickly, compared to how long Piccolo and Vegeta took.
He also seemed to be wary of Vegeta even after he started living on Earth although they're pretty much ignoring that in the recent productions. Tenshinhan being the first to think that Vegeta might be betraying them in the Super version of RoF is the only reference to that so far through all of the recent material.
But, really, what hurts his popularity compared to the later rivals is that he never really got a power up that put him on high tier again after Goku surpassed him for the first time. So, he never got to be portrayed the powerhouse during Z itself. Piccolo was the strongest while Goku didn't arrive and got the two fusions, giving him relevance up to the Cell Saga, and Vegeta is hanging around there even nowadays, but once Tenshinhan was surpassed thanks to the true sacred water he never really got anything to place him on Goku's level again or actually give him some narrative focus for a while. And that's on top of being absent during all of Namek due to being dead.
Like are you fucking kidding me? It's as simple as this, red hair "base" god - Saiyan God. Blue hair - Super Saiyan God. How did they not go with that?! And that would fit the theme of Super being almost a reboot too.
Probably because when SSJ God was created they had no idea they'd create SSJ Blue. The SSGSS name is pretty pointless anyway. It's only used in merchandising. It's never mentioned in the show or movie, and only mentioned in the manga to point out how silly it is.