Just because an exercise is harder does not make it better for your body. Just because an exercise is more challenging does not mean it is going to change your body the way you want it to.
As an example let’s look at the exercise Roll Up. For many people it’s hard to perform the Roll Up smoothly and efficiently because the lower back, hip flexors and abdominal muscles are not in proper balance. Performing a straight leg Roll Up may be harder for you. You may end up using momentum aka “flinging” to get up off the floor or maybe your feet pop up. Your hip flexors and lower back may be tighter than your abs are strong. In this case you may eventually stronger overall but you will likely have the same imbalances as you have now. Basically your hips flexors will get stronger and stronger but your abs will not have the opportunity to get stronger too because ether hip flexors are taking over.
However, if you perform a bent leg or assisted Roll Up, it may seem easier but it will be more effective and promote the changes in your body that you are working towards. This variation will not use your hip flexors as much and therefore your abdominals will be recruited more and will get stronger. Rolling back down and bending your knees as you go will allow your lower back to open and release which will allow your spine to peel off the mat "bone by bone” without popping or flinging.
Over time this “easier” variation will allow you to use your core muscles more release your lower back and hip flexors more which will have an overall better effect in your body resulting in increase strength and alignment. Rather than exercising harder, set a goal to exercise smarter and more efficiently. That’s where the results you are hoping for will come from.