Often in training there are little things that can be up for debate for what works best and applying to a particular style. I've been through many styles of training; high rep workouts, heavy lifting, sprinting, focused tension on specific exercises, animal moves and circuit training; the thing I've come to grips is working best on a style of training that gave me the condition to not always rely on high rep workouts such as push-ups & squats in the triple digits or higher. Not that I don't believe they work, they do but there's far much more to training than focusing purely on high rep calisthenics.
What I look for is specific elements that don't take a long ass time and focusing purely on specific exercises that can be as effective strength wise either through high repetition or utilizing tension for lower reps. Take the push-up for example; I've been through the ringer of only as much as 5 reps in a single set and have hit more than 500 in a single workout; the true effectiveness for me is using muscle control that gets me only a few reps but just hits me like a Mack truck. I do believe High reps works beautifully but after a period in my eyes, it becomes boring, drags along and I don't have the energy to do anything else. The only true purpose to do this type of training is if you're an athlete and needing to be in top condition for your sport or to test yourself to see how far you can go.
I prefer Isometrics & Bridging over most these days and because I've become so enthralled with DVR Exercises, calisthenics is more of a background thing. You don't need to do a ton of reps in order to get in shape. Its great to have that kind of strength & endurance but sometimes you need to step away and test out other things. High reps is also time consuming so if you only have a few minutes, you won't be doing 500 reps of anything but you can do Isometrics, Yoga, Qi Gong, DVR Exercise, Bridging and Gymnastic Type Exercise. I believe in the quality in movement and isometric holds so wouldn't it be better to do a movement that demands quality or just go through the motions and screwing up your form in the process because trust no matter how you slice it, very high reps will cause you to lose your form in one manner or another and if you do it too often that leads to injury. The other thing on that count is how you recover, its important to rest up or do something a little different otherwise you can strain something and it'll bite you in the ass.
Do they truly matter? That's up for you to decide and depending on what you focus on. I love the excitement of training and putting together a workout or sets of workouts throughout the day that takes in quality breathing, energizing effects of particular exercises and making the most out of it and not always striving to do a great level of repetition and lose my sight on what's important or other things. High reps have their place and its ok to not do them if you don't want to but its also important to learn what you're capable of and making a note that you have the ability to do something amazing. Regardless of what you do, learn the value of quality over quantity.