Luffy (and Gamerbee) are scared that people are gonna stick to top 5 in this game for the wins.
I can see why. It's their job to win tournaments, and if you ain't winning, you ain't making that dosh.
But on the flipside, I'd hope that'd make people more competitive and willing to counterpick/try other characters. Top tiers don't always cover every single matchup, and hopefully that leads to people having a few pockets they bring out. I don't mind characters being used as "tools" because there's potential to see them not only used in different ways (i.e., this Ken plays like a nut so I need someone that fits my style and that can keep pace with him at the same time) but get more character variance.
If the game is balanced for it, that is. If the gaps are too large between the characters, it might just be worth it to rock top tiers all damn day and say fuck you to pockets. I don't think SFV promotes just picking a character and playing the most "optimal" way compared to, like, 4, but we'll see when the changes for this season align. I'm feeling pretty positive, but you never know.