Heathpack 

I hear what you're saying, and I suppose even without a training plan if you're paying attention, you might get something out of a power meter. But I'm mostly with @FLvector, most of the utility of a power meter is for training purposes.

For example, I use power numbers to hit specific targets during interval workouts. Of course you can do intervals randomly without a training plan but intervals by their very nature are typically used to achieve specific purposes, they work best if theres a "big picture" training plan.

I use power data to some extent on a road ride, but mostly to make sure I'm riding at the intensity my coach has prescribed. You don't get much out of it without knowledge of your FTP. Which means testing or at least including rides periodically that substitute for a test. You also need to factor in all the variables that affect power output- ambient temp, hydration, nutrition, altitude, fatigue on the ride, cumulative fatigue from recent rides vs rest, goals of the ride. It's not just about outputting maximal power on every ride, it's about outputting appropriate power on that day's ride to meet the goals of the ride. It's not even 100% about tracking all this in your software program, because some factors that affect power output (like ambient T and altitude) are not accounted for at all by these programs, you have to factor that in on your own.

So I guess when I think of a power meter and what I get out of it, the maximal effect comes with how it influences/defines my overall training plan and how it is an important language that my coach & I use for communication. Which is not to say that there's no utility for a power meter outside of this context, just that you'll get way less out of it. IMO a power meter is pretty essential for the coached cyclist with a formal training plan. Whether this is self-coached vs hired coach. But for the non-training cyclist, it's very much optional and a matter of whether the cost is a factor for you or not. You will see some numbers which you may understand to varying degrees, depending on how fully you choose to educate yourself. If you're not interested in training, you might be better off spending the power meter budget elsewhere on the bike.

FYI, I got my power meter before I had my coach and when I had a sort-of self-coached training plan. I got it upon recommendation of a BF friend who knew exactly where I'd go with it. But I was pretty serious about my cycling all along, not exactly an "average enthusiast," he was correct in his prediction that a power meter would lead to coaching and an overall better training plan and that all of that would suit me to a "T". He was 100% right, I love training and my coach and power data, it way enhances my enjoyment of cycling 100%. So I'm not saying OP shouldn't get a power meter. Just when I think of "average enthusiast" I don't think of people like me who just keep pushing and training and getting up at 4am to do two hour trainer workouts and frequently can't ride with who they want to because that ride would not meet the day's training objective . I think of the guy who rides a few times a week on a 20-30 mile group ride and really wants to just ride with friends and maybe get better over time. That person can immensely enjoy cycling without a power meter being a vital part of the picture.