Beyond the 250cc, it's not about need, it's about want. And there is absolutely nothing wrong with that. He or she is not stupid for wanting whatever he/she wants. He or she is not you and is free to be. To each their own.
I commute every day on a bike. For that reason, I prefer the liter bike, that is the bike is not 'wrung out' at freeway speed... about 4K-5K RPM at freeway speed. The part I like is the instant power available if I ever need to get out of a tricky spot before it becomes worse.
You don't have to go fast to have fun and that still applies on a liter bike. The bike is nimble enough that I have have plenty of fun in the twisties as well. Maybe it's not as fun as you would think I might have on a smaller bike, but fun is subjective.
If that's what your friend wants, you can give your opinions, plus and minus, logically, financially, etc. In the end, if your friend can afford it and it's what your friend wants, so be it.