I always use CO2, regardless of whether the tank has lower light plants or not. It's possible to have a nice tank with healthy growth without, and plenty do this, but after trying both methods and seeing the results, I don't bother thinking about it anymore. Besides, once the initial investment is made, the cost is close to nil to refill the tank once every few months. I really don't see CO2 injection as a hassle or a big deal-just an automatic part of any planted tank I keep.
Also, using CO2 will alow you to play around with the lighting and increase it over time should you choose to do so for faster growth; this isn't an option for a tank without it (up to a point it is, but not to the same extent).
if you're on the fence, I say go for it!