I've seen a bit of consensus on here about the idea that everyone should refrain from updating from the stock firmware (I don't know if it's actually called 1.0, I'm just using these numbers for the sake of argument) to increase the chance of being able to hack the system in future. Firstly, I've never known a hack to be released which requires an older version of firmware to the current one available at the time the hack was released, probably because companies rarely patch exploits that don't yet exist in the wild, and are notoriously bad at detecting their own vulnerabilities and addressing them before hackers do.
But consider this. You stay on 1.0, shunning added functionality, 3DSware etc, holding out for a hack. You log on to GBATemp after a few days away and glory! An exploit has been found! Someone's found a vulnerability in the 3DS movie player which can cause a buffer overrun and execute unsigned code! But wait... You don't have the movie player, that came with 1.1. Best update after all so I can run the hack. Wait, Nintendo quickly patched the exploit and when you update you end up on 1.2, where the exploit no longer works. Fuuuuuuuuuuuuu-
But consider this. You stay on 1.0, shunning added functionality, 3DSware etc, holding out for a hack. You log on to GBATemp after a few days away and glory! An exploit has been found! Someone's found a vulnerability in the 3DS movie player which can cause a buffer overrun and execute unsigned code! But wait... You don't have the movie player, that came with 1.1. Best update after all so I can run the hack. Wait, Nintendo quickly patched the exploit and when you update you end up on 1.2, where the exploit no longer works. Fuuuuuuuuuuuuu-