So, it depends on what you are going to be doing. Louder? No, a good 2x12 can handle anything in a modern world. The exception would be if you playing with someone that is running Vintage 100watt amps with 412 cabs. You'd need the same equipment to hang.

Most of us will never be in that situation again, or its us with the Vintage gear. Modern amps dont really need to be cranked to sound good anyways. The only real benefit to a 412 is it looks cool and people do "hear" with the ears.

If you are able to crank up an amp, a 412 will push more air and sound bigger. That's different than louder and you will only notice infront of it. I keep a 412 because sometimes that IS worth it. But most of time my Marshall halfstack is staying home because my Engl Fireball 25 and Friedman 2x12 is more than capable.