As a diver, you're already diving Nitrox. The air we breath is Nitrox. Nitrox is any combination of Oxygen and Nitrogen. The air we breath is approximately 21% Oxygen and 79% Nitrogen. There are other trace gases as well.
Your question is really "Should I get EANitrox Certified?"
The answer is NO.
Air works just fine and has for many many years. While I am a Certified Nitrox Instructor and have been Nitrox certified myself for more than a decade, I have not found a reason to use it in many years... at least not a good enough reason to spend the extra money on it.
You see, Nitrox was really introduced to the recreational dive industry as a way to make money for dive shops. In the early days, there was great debate over whether it was even safe for recreational diving.
While there are certainly situations where EANitrox may make sense, generally speaking these situations are beyond the scope of entry level recreational diving and even advanced recreational diving.
With the new limit of certification to 60', EANitrox makes little sense. When it comes to deep diving from 60' - 130', it certainly has applications - but these applications also come with increase risked from its use.
Increased partial pressures of oxygen can be toxic and deadly to divers who wander to deep while breathing it. Understanding the MOD (maximum operating depth) is critical.
This is the basis for why I do not dive it. I may purposely want to deviate from my dive plan, say on a wall dive or wreck dive and go deeper than my plan. My EANitirox mix could become a detriment on such dives. With less limitation on air dives, I will always choose air.
Of course with air, you may have a more limited time than you would on Nitrox, but you're in no danger of oxygen toxicity and you can always simply carry more air and do longer safety stops.
Decompression diving, while outside the true scope of entry level recreational diving, is a safer, less costly approach with proper education and planning.
I also happen to be one who believes DECO stops produce some of the most chance and exciting open water encounters you'll ever have... from open ocean sharks to whales, pods of dolphins, ocean sunfish etc... these are things I may never have had such exciting encounters with if I wasn't "hanging out" on the line.
After a good Open Water course, the only thing you really need to do is go diving. Get some experience and explore your world. Nitrox is definitely one place not to waste your money.