If you were talking about a Sharpshooter, I would be more sympathetic. Barbarians start to slow down as battles start to spread out and enemy casters start to slow them down. Melee martial not fun at high level (save for perhaps paladin).
You're the one who brought up the high levels. I don't care diddly for what level 17 does. Last survey result showed that the vast majority of players are still playing levels 1-6, and most realistically believe they won't ever pass level 10. Levels 1-10 are the levels that need to be done right, because those are the ones that are actually played.
Even then, I don't buy into the theoretical "melee starts becoming bad" idea. You don't see that in their two published adventures, RoT or PotA. High levels don't mean the battlefields are suddenly sniper contests.
I do agree they should have added bonus spell lists to the sorcerer. Not sure why they didn't. 15 spells is ridiculously weak. Metamagic isn't good enough to make up for the limit.
It seems they realized 15 was too few after the fact and they're making it up with the new subclasses. I agree that bonus spells would be great. Also don't get me started on metamagic: the big selling point on sorcerers, you get 2 early on, then you have to wait eons for your 3rd and 4th? That's it. And you don't get to retrain them either. 4 total spread over 17 levels.
Let's not also pretend you can't convert spell slots into more sorcery points to twin more. You're attacking at range. As you admitted, you shine pretty bright AoE. Mr. Barbarian looks good now. We'll see how he looks at higher level.
Of course I can convert spell slots. It's highly inefficient, and makes me waste my precious resources though. It's also the same resource that gets me more spells, which Wizards get as a separate resource. Cannibalizing my spells to get more Twin Scorching Rays is -- was, a fast way to being stuck with crappy Fire Bolt for a long time.
Barbarian has looked spectacular from levels 1-7. I look at future spells and don't see that changing any time soon. You can Twin Disintegrate once per day eventually I guess?
Though I will admit the sorcerer needs some tweaking. I can see why they put this limit in. It affects the Evoker as well and makes Sorcerer and Evoker consistent. Twinning might lead to problems with future spells they may design. Specifically for scorching ray and magic missile, I don't see an issue.
All I can do is show you the math on why it was fine and now crappy. You've heard my personal experiences, and you can see my spell list isn't some fountain of utility. If that doesn't move you then we agree to disagree!
I personally wouldn't choose a Sorcerer with this errata. Maybe my last hope is a Warmage port from 3.5 . Absolutely no utility spells so people can't harp on that. Then give it blasty spells that keep pace with the martials. Would make me happy.
