Am I correct in assuming this was inspired by Brian_F's video today?
I'm the Ken player in the video and I think I can give some insight - I can't say this is the case in every Street Fighter game, but in newer installments the character is honestly designed for players who like Ryu's moves but want easier access to damage and approach. Ryu generally gets faster attacks, better ranged options and oftentimes higher damage, but Ken is given faster walkspeed, easier combos, and more options to make big guesses and get in.
In the video I'm playing pretty autopilot (I had no idea it was Brian and I was fishing for points by this point in the night lmao) but all of the insane risks it looks like I'm taking are honestly less nutty than they look. My only experience vs. Seth is against online Seth players, and two moves they do at random pretty often are the VS1 with the vaccuum effect and the spin kick that's advantageous on block at the cost of slow start-up - the heavy hurricane kicks you see me doing seemingly at "random" are honestly me underestimating the other player and trying to hit him. Is it a risk? Of course, but I'm eating a jab combo punish at worst and an anti-air at best! The same goes for Ken's EX divekicks which are similarly useful for clearing over projectiles or catching moves on the ground with slow start-up. Any character has the option to take similar risks by jumping in, but some of Ken's special moves, by design, let him mix up these approaches and get in "for free". Other characters have similar (and stronger) options in terms of movement and making big gambles but with other drawbacks - Cammy and Karin for example have lower health and you're not going to catch either of them throwing a hadouken.
Then you have other games like Smash where Ryu's Shoryuken kills earlier, but only if you land the sweetspot - Ken's kills later, but the attack has huge knockback no matter what angle it catches you from. They're both designed as entry-level characters (and don't get me wrong, seeing either of them played at top-level is as entertainingly Street Fighter as Street Fighter gets) but Ken is actively encouraged to play in a more high-risk way. In the wrong hands, the character ends up looking as scrubby as you would expect. Hope this was insightful!