They may test the waters of other workout styles, feel unimpressed, and wonder whether they should continue to do something they don't like. And it's not just the cards bunnies that experience this. It's easy for any of us to get super absorbed in the style of exercise that we like (Pilates, Yoga, Lifting, etc), and then completely turn our nose up at any other workout style.
The short answer is – maybe.
If your goal is simply improved heart health, released endorphins, relaxation or stress relief, then do anything that makes you happy and keeps you moving. Overall health should be a huge consideration in what workouts make you happy. If you love your classes, then keep taking them. If you love running marathons, by all means keep doing them. Happiness is what will keep you motivated to continue to do something.
However, if you have specific goals in mind, there might be workouts you have to do in order to get the results you want, even if you don't like doing it. This means depending on what your goals are, things need to be done to help get you there. Want to run a 10k? Ramp up the endurance work. Wanna compete in a Strongman? Spend a bit more time on strength building. Improved flexibility and core strength? Break out that yoga mat. Looking to get ripped? Gonna need to apply some resistance to those muscles, if you ever wanna see them.
In other words, you're going to have to challenge yourself in new (and completely different) ways to reach each new (and completely different) goal. Even if you don't particularly like the challenge activity in question.
But it doesn't mean that you have to completely eliminate the exercises you do love in place of these.
What it does mean, is that you have to be aware of what you are doing and what results you should expect from it. If you are doing nothing but cardio, you cannot expect to get a ripped and muscular body (and say goodbye to that Strongman!). Cardio will give you a specific body style, but it is likely not the one you are hoping to get!
If you wanna become more flexible, but aren't willing to invest the time in the activities that will achieve better mobility/flexibility, then don't get upset when you can't go quite as deep into that squat – or when you discover that you're a bit more accident prone – than you like.
Bottom line – if you're just starting out, or don't have specific goals: do the activities or workouts that make you feel good and make you want to get off the couch and DO them. If you haven't found what that is yet, keep trying! There are so many different ways to move your body. Find what you love. However, if you are trying to get goal specific (i.e. looking to build muscle and have that “toned” look), then you might need to be open to new workout styles (read: pick up the weights), even if you don't like them.