Not sure I'd agree with that.
It's not like there's a learning curve for switching to 64bit, so you'd better start learning now!
There isn't you just choose another ISO. For most people you wouldn't even know which version you're running.
If there was some huge performance advantage then it would be a no-brainer but there isn't (last time I checked). Though it seems like there should be given that you can handle twice as many bits per cpu cycle.
Pretty much the only reason I can think of for running 64bit is if you need >4GB of ram.
Advantages of not running 64bit; code is more tested and hence more stable. Though it's probably marginal.